Anatomy notes collection

Haytham Bayadsi, 2009/2010

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Dear Students,

In those pages you will find a collection of notes about the gastrointestinal & respiratory tracts,
the heart, as well as the topography of the thoracic and abdominal walls together with the
retroperitoneal cavity and mediastinum. I have added also the topography of the neck section
including fasciae, triangles and Nuchal region. at the end of the file you will find an appendix
containing hand made drawings that can be useful for the preparation for the midterms, semifinal
or final exams. (in the printed version only)
These notes were summarized and collected from different sources that I list here:
- Moore: Clinically oriented anatomy
- Thieme: Internal organs (vol. 2)
- Rohen Yokochi color atlas of anatomy
- BRS anatomy
- Kovacs anatomy
- Instant anatomy website
- Grey's anatomy
- Netter Atlas
- Anatomy lectures at the department of Anatomy, Histology & Embryology
- Dr. Madarasz's notes & drawings
- Dr. Somogyi's & Dr. Altdorfer's file about peritoneum & anatomical cartoons
- Dr. Altdorfer's & Dr. Hanics's file about the branchial apparatus

The different chapters of this file were revised by some of the teachers of the department of
Anatomy, Histology & Embryology (listed in alphabetical order) in order to meet with the
demands and requirements of the department:
- Dr. Altdorfer, Károly: Esophagus, stomach, small intestines, large intestines, peritoneum,
heart
- Dr. Barna, János: Liver & gallbladder, porto-caval anastomosis, pancreas, spleen
- Dr. Gallatz Katalin: Kidneys, adrenals, ureters, aorta, IVC, external carotid & maxillary
arteries
- Dr. Madarász, Magdolna: Trachea, pleura, lungs, diaphragm. heart
- Dr. Somogyi, György: Abdominal wall, inguinal region, mediastinum, peritoneum
- Dr. Székelyi, Andrea: oral cavity, teeth, tongue, palate, pharynx
- Dr. Tótpal, Géza: External nose, nasal cavity, larynx

Please understand that these notes do not guarantee the passing grade in the exams or replace the
original atlases or books suggested by the department. The main purpose of these notes is to
orientate you around the important and main points & aspects required by the department of
Anatomy, Histology & Embryology during the course of your preparation toward the final exam
at the end of the 2nd year.
If you do encounter any type of mistake or you have any ideas or suggestions please contact me
at: haythamtb@gmail.com

I would like to thank the teachers who participated in revising these notes for their time & effort
and continues support not only for me, but also for the medical and dental students at the
department of Anatomy, Histology & Embryology. I would like also to thank Yoav Litani (2nd
year) for his aid in the graphic design of most of the illustrations.

Wish you all the best & lots of luck

Haytham Bayadsi

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Table of contents:

THE GASTROINTESTINAL TRACT ............................................................................................... - 4 -

THE ORAL CAVITY ...............................................................................................................................- 5 -
THE TONGUE............................................................................. ...........................................................- 7 -
THE PALATE............................................................................. .......................................................... - 14 -
THE TEETH............................................................................. ............................................................ - 18 -
THE SALIVARY GLANDS .....................................................................................................................- 23 -
THE PHARYNX............................................................................. ....................................................... - 27 -
THE ESOPHAGUS ................................................................................................................................ - 34 -
THE STOMACH.................................................................................................................................... - 36 -
THE SMALL INTESTINE ......................................................................................................................- 40 -
Duodenum............................................................................. ............................................. - 40 -
Jejunum & Ileum............................................................................. .................................. - 43 -
THE LARGE INTESTINE......................................................................................................................- 45 -
Cecum & Appendix............................................................................. .............................. - 46 -
The Colon............................................................................. .............................................. - 48 -
Sigmoid colon:............................................................................ ....................................... - 49 -
The Rectum..........................................................................................................................- 51 -
The Anal Canal............................................................................. ..................................... - 54 -
THE LIVER............................................................................. ............................................................. - 57 -
BILIARY DUCTS AND GALLBLADDER.................................................................................................- 63 -
Communication between portal and systemic veins (Porto-caval anastomosis) .......... - 66 -
THE PANCREAS................................................................................................................................... - 68 -
THE SPLEEN........................................................................................................................................ - 71 -
THE RESPIRATORY TRACT ......................................................................................................... - 74 -
THE NOSE............................................................................................................................................- 75 -
External nose............................................................................. ......................................... - 75 -
Nasal Cavity............................................................................. .......................................... - 77 -
PARANASAL SINUSES ..........................................................................................................................- 84 -
POSTERIOR NASAL APERTURES (CHOANAE) .....................................................................................- 88 -
THE LARYNX............................................................................. ......................................................... - 89 -
TRACHEA............................................................................. ............................................................... - 97 -
THE PLEURAE (MEMBRANA SUCCINGENS) ...................................................................................... - 98 -
THE LUNGS............................................................................. .......................................................... - 101 -
GROSS ANATOMY OF THE RETROPERITONEAL ORGANS................................................ - 108 -
THE KIDNEYS............................................................................. ...................................................... - 109 -
THE URETER..................................................................................................................................... - 115 -
THE SUPRARENAL GLANDS (ADRENALS) ........................................................................................- 117 -
SUBDIVISION AND TOPOGRAPHY OF THE AORTA ...........................................................................- 119 -
THE INFERIOR VENA CAVA ..............................................................................................................- 121 -
THE THORACIC DUCT.......................................................................................................................- 122 -
CELIAC TRUNK (HALLER TRIPOD) ..................................................................................................- 124 -
SUPERIOR MESENTERIC ARTERY.....................................................................................................- 126 -
INFERIOR MESENTERIC ARTERY .....................................................................................................- 129 -
GROSS ANATOMY OF THE HEART & MEDIASTINUM ........................................................ - 130 -
THE HEART.......................................................................................................................................- 131 -
Location.............................................................................................................................- 131 -
Surfaces............................................................................................................................. - 131 -
Anatomical Borders (Margins) ...................................................................................... - 131 -
Projections............................................................................. ........................................... - 132 -
PERICARDIUM............................................................................. ...................................................... - 132 -
Pericardiac Sinuses...........................................................................................................- 133 -
LAYERS OF THE HEART ....................................................................................................................- 134 -
EXTERNAL FEATURES OF THE HEART .............................................................................................- 135 -

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CAVITIES / CHAMBERS OF THE HEART ........................................................................................... - 136 -

FIBROUS SKELETON OF THE HEART (ANNULUS FIBROSUS CORDIS) ..............................................- 141 -
VALVES..............................................................................................................................................- 142 -
AUSCULTATION OF THE HEART VALVES .........................................................................................- 145 -
VASCULATURE OF THE HEART ........................................................................................................- 146 -
VENOUS DRAINAGE OF THE HEART .................................................................................................- 147 -
THE CONDUCTING SYSTEM OF THE HEART: ...................................................................................- 148 -
NERVOUS SUPPLY OF THE HEART ...................................................................................................- 149 -
PERCUSSION OF THE HEART ............................................................................................................- 151 -
SHADOW OF THE HEART (SILHOUETTE / X-RAY OF THE HEART) ..................................................- 151 -
THE MEDIASTINUM .........................................................................................................................- 153 -
Supracardiac mediastinum, Layers from anterior to posterior .................................. - 154 -
Posterior Mediastinum layers, contents ........................................................................ - 156 -
TOPOGRAPHY OF THE THORACIC CAVITY .......................................................................... - 158 -
STRUCTURE OF THORACIC CAGE ....................................................................................................- 159 -
VERTEBRAE, IV DISK, LIGAMENTS .................................................................................................- 160 -
RIBS...................................................................................................................................................- 162 -
MUSCLES OF THE THORACIC WALL ................................................................................................- 165 -
FASCIA OF THE THORACIC WALL ....................................................................................................- 167 -
NERVES OF THE THORACIC WALL ...................................................................................................- 168 -
VASCULATURE OF THE THORACIC WALL .......................................................................................- 172 -
THE DIAPHRAGM..............................................................................................................................- 177 -
TOPOGRAPHY OF THE ABDOMINAL WALL & INGUINAL REGION ................................ - 180 -
FASCIA OF THE ANTEROLATERAL ABDOMINAL WALL, LAYERS .................................................... - 181 -
ABDOMINAL MUSCLES .....................................................................................................................- 182 -
THE RECTUS SHEATH ......................................................................................................................- 184 -
NERVES OF THE ANTEROLATERAL ABDOMINAL WALL ..................................................................- 186 -
VESSELS OF THE ANTEROLATERAL ABDOMINAL WALL ................................................................. - 186 -
INGUINAL REGIOS ............................................................................................................................- 187 -
Inguinal canal....................................................................................................................- 188 -
LUMBAR (DORSAL) REGION ...........................................................................................................- 191 -
The Thoracolumbar (Lumbodorsal) fascia .................................................................. - 191 -
THE PERITONEUM AND PERITONEAL COVERINGS ..........................................................................- 193 -
Embryology of the Peritoneum ...................................................................................... - 196 -
Subdivisions of peritoneal cavity.................................................................................... - 198 -
Omentum…………………...……………………………………………………………- 201 -
BODY SURFACE DIVISIONS AND IMPORTANT LINES ........................................................................- 204 -
INTERNAL SURFACE OF THE ANTEROLATERAL ABDOMINAL WALL, PREPERITONEAL SPACE .......- 206 -
HERNIA..............................................................................................................................................- 207 -
FASCIA & TRIANGLES OF THE NECK, NUCHAL REGION ................................................. - 208 -
FASCIA OF THE NECK .......................................................................................................................- 209 -
PERIPHARYNGEAL SPACE ................................................................................................................- 211 -
Parapharyngeal space...................................................................................................... - 211 -
The Retrovisceral space................................................................................................... - 212 -
CERVICAL REGIONS/TRIANGLES AND THEIR CONTENTS: ..............................................................- 215 -
NUCHAL REGION ..............................................................................................................................- 226 -
THE EXTERNAL CAROTID ARTERY ................................................................................................ - 220 -
THE MAXILLARY ARTERY (INTERNAL MAXILLARY ARTERY) ....................................................... - 223 -
FACIAL ARTERY (EXTERNAL MAXILLARY ARTERY): .....................................................................- 226 -

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The Gastrointestinal tract

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The oral cavity

Different parts of the oral cavity:

- The vestibule: that part of the mouth bounded anteriorly and laterally by the lips and the
cheeks, posteriorly and medially by the teeth and/or gums, and above and below by the
reflections of the mucosa from the lips and cheeks to the gums.
- The oral cavity proper: the space between the dental arches, limited posteriorly by the
isthmus of the fauces.
o if the jaws are totally closed and dentition is normal then there is no connection
between the 2 parts of the oral cavity, except behind the last molar tooth

Borders of the oral cavity:

- Superior border (Roof): Hard (anterior) & Soft (posterior) palates

- Inferior border (Floor): the muscular floor or the diaphragm of oral cavity, formed by
the Mylohyoid muscles that arise from the mylohyoid line to the medial raphe and to the
hyoid bone. Above this floor and near the midline there are the 2 Geniohyoid muscles
that also can be considered as part of the inferior border (Floor)
- Lateral border: teeth arches (cavity proper) or the cheeks formed by the Buccinator
muscle, Bichat's fat pad and mucosa (the whole oral cavity)
- Anterior border: the lips
- Posterior border: open, the Isthmus of Fauces, bordered by:
Superior: soft palate
Inferior: root of the tongue
lateral: palatoglossal and palatophayrngeal arches
(Anterior & Posterior Palatine Arches, inside them
muscles with the same names)

The vestibule of the oral cavity:

- The lips are found anteriorly, guarding the entrance to the mouth. Both lips are connected
laterally at the corners of the mouth
- The upper lip reaches the base of external nose and to the Nasolabial fold
- The lower lip reaches the chin-lip groove (mentolabial fold)
- The Philtrum is the groove that extends downward from the nose over the midline of the
upper lip
- Each lip has 2 parts:
o External cutaneous part (covered by stratified squamous keratinized hairy
epithelium)
o Internal mucous part (covered by stratified squamous non-keratinized epithelium)

** The Red area of the lip (Vermilion border) demarcates the border between the 2
parts, its has a thinly keratinized type of stratified squamous epithelium deeply
penetrated by well-vascularized dermal papillae
- The mucobuccal or mucolabial folds are the line of flexure of the mucous membrane as it
passes from the mandible or maxillae to the cheek or lips respectively
- The anterior upper and lower mucosal folds in the vestibule are called the Frenulum of
lips

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Gums (gingivae):

The dense fibrous tissue and overlying mucous membrane, which envelops the alveolar
processes of the upper and lower jaws and surrounds the necks of the teeth, has 2 parts:
o Pars fixa gingivae: or the proper gingiva, the attached part of the gums that is
tightly connected to the periostieum of the neck of teeth and alveolar processes of
jaws, it is demarcated from lining mucosa on the facial aspect by a clearly defined
line which marks the mucogingival junction (Girlandiform line), and, in contrast
to the lining mucosa, is keratinized and lighter in color; on the palatal surface, the
gingiva blends imperceptibly with the palatal mucosa.
o Pars libera (free) gingivae: or the marginal gingiva, the most coronal part that
extends beyond the alveolar bone by 1-2 mm surrounding the tooth, it is
supported and stabilized by the gingival fibers and composed of:
Interdental papilla: thickening (seen as an elevation) of the gingiva that
fills the interproximal space between two adjacent teeth.
Gingival limbus: the tip of the marginal gingiva, encircling the neck of
teeth as a belt at the dentinoenamel junction of tooth
The gingival sulcus: the space or furrow between the surface of the tooth and
the free soft tissue gingiva

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The Tongue

A mobile muscular organ that is covered by a mucous membrane (stratified squamous non-
keratinized epithelium), partly found in the oral cavity (2/3) as pars papillaris (Presulcal), partly
in the isthmus of fauces (1/3) as pars follicularis (Postsulcal) with the lingual tonsil (the border
between the 2 parts is the V-shaped terminal sulcus lined anteriorly by the group of the
Circumvallate papillae, in the middle of the terminal sulcus we can find the Foramen Cecum,
which is the remnant of the Thyroglossal duct in thyroid gland development.
At rest, the tongue occupies the entire oral cavity proper
Main functions:
a. Forming words during speech
b. Mastication
c. Squeezing food into the pharynx
d. Taste

Parts of the tongue:

- Body (corpus)
- Apex (tip)
- Root
- Dorsum (back): has the median sulcus of tongue
- Inferior surface: has the frenulum, deep ligual vein and fimbriated fold

Connections of the base of tongue:

a. Hyoid bone (by the Hyoglossus muscle)

b. Epiglottis: by,
- 1 median glossoepiglottic fold
- 2 lateral glossoepiglottic folds
Between these 2 fold folds we find the Epiglottic Valleculae

c. Soft Palate: by the Palatoglossal arch

d. Pharynx: by part of the superior constrictor muscle (4th part, Glossopharyngeal)
e. Mandible:
- by the Frenulum lingua: a fold under the surface of tongue, formed by the mucus
membrane, on both sides of this fold we find the Lingual Valleculae
The Sublingual caruncula is a papilla on each side of the base of the
lingual frenulum, in the Valleculae, which is the location of the opening
of the Submandibular duct + main sublingual duct
- by the Genioglossus muscle (from mental spine)

Lingual papillae:
Numerous variously shaped projections of the mucous membrane of the dorsum of the tongue;
that have mechanical and sensory (taste) functions, there are 4:
a. Circumvallate papillae: anterior to the terminal sulcus. Surrounded by circular trenches
(fossa), and having a slightly raised walls (vallum) of which studded by taste buds.
b. Foliate papillae: on the lateral sides of tongue, poorly developed in humans, has taste
buds.

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c. Filiform papillae: arranged V-shaped rows, parallel to terminal sulcus, keratinized on the
top and contain afferent nerve endings; sensitive to touch. At the apex of tongue they are
arranged transversally.
d. Fungiform papillae: scattered among the Filiform papillae, and most numerous at the
apex and sides of the tongue. Mushroom shaped and appears as pink or red spots. Have
taste buds.

Extrinsic muscles of the tongue:

Arise from structure nearby the tongue, and their fibers insert into the tongue in a 3-D
network. Mainly control the position of the tongue inside the oral cavity
The first 3 muscles are innervated by the Hypoglossal nerve (XII) while the Palatoglossus is
innervated by the Pharyngeal plexus (Glossopharyngeal nerve IX & Vagus nerve X)

1. Genioglossus: Depression of tongue (more anterior fibers) and protracting the tongue
outside the oral cavity (posterior fibers, only muscle that protracts tongue!)
Origin: Mental spine (superior part)
Insertion: fans out from apex to the root of tongue

2. Hyoglossus: depresses and retracts tongue backwards

Origin: greater horn of hyoid + body of hyoid
Insertion: lateral side and inferior surface of tongue

3. Styloglossus: pulls the tip backward, and pulls the whole tongue upwards & backwards
Origin: styloid process + stylohyoid ligament
Insertion: side up to the anterior aspect of tongue

4. Palatoglossus: Elevates posterior part of tongue

Origin: palatine aponeurosis (soft palate)
Insertion: side of tongue

Intrinsic muscles of tongue:

group of fibers running in 3 principal planes and attached to the connective tissue framework
of tongue that is composed of the Lingual Septum (fibrous, dividing the tongue in 2 halves)
and the Lingual aponeurosis (tough sheet, between the mucous membrane and muscles)
Also all of these muscles innervated by the Hypoglossal nerve (XII)

1. Superior longitudinal: curls tip and side superiorly

2. Inferior longitudinal: curls tip inferiorly

3. Transversus: narrows and elongates tongue

4. Verticalis: flattens and broadens tongue

** An important note: In case of hypoglossal nerve half paralysis (Hypoglossal paresis), the
tongue will protrude, but the Genioglossus, Transversus and Verticalis muscles of the healthy
side will push the ipsilateral (same side) longitudinal muscles forward, and thus the tongue

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will turn (point) towards the diseased side (paralyzed) because it offers no resistance to the
healthy muscle.
E.g. if you ask the patients to protrude his tongue, and his tongue will deviate to the left it
means that the Left Hypoglossal is damaged, which means that it could be a problem in the
Right hemisphere of brain (because of the decussating or crossing nerve fibers in brain

Innervation of tongue:

- Motor innervation: Hypoglossal nerve (XII): for all muscles of tongue, except the
Palatoglossus (innervated by the pharyngeal plexus)

- General sensory innervation (touch, temperature):

o Anterior 2/3 (Presulcal): Lingual nerve, branch of mandibular nerve (CN-V3)
o Posterior 1/3 (Postsulcal): Glossopharyngeal nerve (CN-IX)

- Taste sensation:
o Anterior 2/3 (Presulcal): Chorda tympani nerve, branch of Facial nerve (CN-
VII)
** But the Circumvallate papillae, located at the border, are innervated by the
glossopharyngeal nerve (CN-IX)
o Posterior 1/3 (Postsulcal): Glossopharyngeal nerve (CN-IX)

**Vagus nerve (CN-X): innervates the tongue from its base, until the epiglottis (folds
and Valleculae)

Taste sensation:
1. Sweetness: at apex
2. Sourness and bitterness: posterior part
3. Saltiness: lateral margin

Vasculature of tongue:

External carotid artery lingual artery branches:

1. Dorsal lingual arteries: supplies posterior part and palatine tonsils

2. Deep lingual artery: supplies the anterior part, the anastomosis between the right and
the left end-branch of the deep lingual artery is called the Beclard or Ranine
anastomosis
3. Sublingual artery: supplies floor of mouth and sublingual glands

- All veins run parallel to the arteries and drain into internal jugular vein, the
Apical veins of the tongue are seen very well on both sides of the frenulum on the
inferior surface of the tongue forming the fimbriated folds

** The lingual artery is the 2nd branch of the External carotid artery (or commonly also
branches from the facial artery, then its known as the Linguofacial trunk), and it can be
recognized as the artery immediately found above the greater horn of the Hyoid bone. It
passes behind 2 different triangles which are important in surgery (control of tongue
bleeding) before it ends up in the medial lingual sulcus:

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1) Pirogoff triangle, borders:

- Superior Hypoglossal nerve (CN-XII)
- Anterior Posterior margin of mylohyoid muscle
- Inferior Tendon of digastric muscle/ stylohyoid muscle

2) Beclard triangle, borders:

- Superior Tendon of digastric muscle
- Posterior free margin of hyoglossus muscle
- Inferior Greater horn of hyoid bone

** Content of both triangles: lingual artery

Lingual grooves (Sulci)

We have to distinguish different spaces or specifically called Lingula grooves between

the tongue and the nearby muscles and structures, we have 2 lingual grooves with
different contents inside them:

1) Lateral groove (sulcus) of the tongue:

Borders:
Medial: Hyoglossus muscle
lateral: Mylohyoid muscle
Superior: Sublingual mucous membrane
Contents:
Lingual nerve
Submandibular duct
Hypoglossal nerve (XII) (more posteriorly)
Sublingual gland (only anteriorly)

2) Medial groove (sulcus) of the tongue:

Borders:
Medial: Genioglossus muscle
lateral: Hyoglossus muscle
Contents:
Lingual artery
Glosspharyngeal nerve (IX) (not totally)

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The Palate
Is the arched roof of mouth and floor of nasal cavity, Separates oral, nasal and nasopharynx
cavities, and has:
o Superior part covered by respiratory mucosa (pseudostratified columnar epith.)
o Inferior part covered by oral mucosa (Stratified squamous non-keratinized epith.)

Composed of 2 parts:
o The Hard palate anteriorly
o The Soft palate posteriorly

Hard palate:
The anterior 2/3 of palate, Composed
of:
- Premaxilla or incisive bone:
the anterior and inner portion
of the maxilla, which in the
fetus and sometimes in the
adult is a separate bone.
- Palatine process of maxilla
- Horizontal plates of palatine
bones

In the middle of the hard palate's mucosa

there is the Raphi palate, and further
between the periostieum and the mucosa we can fine numerous Palatine glands
It has 3 foramina:
a. Incisive fossa (with 2 foramina): contains Nasopalatine nerves (of Scarpa)
incisive papilla
b. Greater palatine foramen: medial to 3rd molar, greater palatine vessels and nerves
c. Lesser palatine foramina: lesser palatine vessels and nerves.

Soft palate:
The posterior 1/3 of palate, motile, has 4 parts:
- Anterior:
Aponeurotic palate, attaches to hard palate formed by an expanded
tendon of tensor veli palatini
- Posterior:
Muscular palate
- Midline: Uvula
- Lateral:
Continuous with the wall of the pharynx by Palatoglossal and
palatopharyngeal arches

Role in Swallowing:
The palate is initially tensed to allow the tongue to press against it, squeezing bolus to the
back of the mouth. The soft palate is then elevated posteriorly and superiorly against the
wall of the pharynx, preventing passage of food into the nasal cavity.

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Muscles of the soft palate:

a. Tensor veli palatini: tenses the palate & opens auditory tube
Origin: Scaphoid fossa & membranous part of the Eustachian tube
Insertion: Palatine aponeurosis, the muscles tendon forms a hook around the
Pterygoid hamulus, so radiating horizontally into the soft palate

b. Levator veli palatini: elevates the soft palate up and backward

Origin: petros part of temporal bone + cartilaginous part of the Eustachian tube
Insertion: Palatine aponeurosis

c. Palatoglossus: elevates posterior part of the tongue + draws the palate to the tongue,
closing the isthmus of Fauces
Origin: Palatine aponeurosis
Insertion: side of the tongue

d. Palatopharyngeus: tenses the palatine + pulls the walls of pharynx during swallowing
Origin: palatine aponeurosis and hard palate
Insertion: lateral wall of pharynx

e. Musculos uvulae: shortens the uvula and pulls it superiorly

Origin: palatine aponeurosis and posterior nasal spine
Insertion: mucosa of uvula

- All muscles are innervated by pharyngeal plexus (Glossopharyngeal IX, Vagus

X), except to the tensor veli palatine, innervated by the a nerve branch of the
Mandibular division of the Trigeminal nerve (CN-V3) which loops around the
Pterygoid hamulus

** Note: To test glossopharyngeal and Vagus nerve function, examine the position of the uvula and its
movement by asking the patient to say "Ah." The soft palate should elevate symmetrically and the uvula
should remain in the midline. The gag reflex can be tested by touching the pharyngeal wall on each side
with a cotton tip applicator. This reflex relies on an intact sensory arc, as mediated by sensory fibers of the
glossopharyngeal nerve to the soft palate, and an intact motor arc, as mediated by the motor fibers of the
Vagus nerve to the soft palate and pharynx. Deviation of the uvula to one side implies a lower motor lesion
of the Vagus nerve contralateral to the side the uvula is deviating to. An upper motor neuron Vagus nerve
lesion will present with the uvula deviating toward the side of the lesion.

Vasculature and innervation of the palate:

Vasculature:
o Greater palatine artery
o Branch of descending palatine artery (From Maxillary artery)
o Lesser palatine artery anastomosis with ascending palatine (From facial artery)

Innervation
o Greater palatine nerve: supplies the gingivae, mucous membrane and glands of
the hard palate
o Nasopalatine nerve: mucous membrane of anterior part of the hard palate
(Premaxilla)
o Lesser palatine nerve: soft palate

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Waldeyer's lymphatic pharyngeal ring, formed by:

a. Palatine tonsils, most frequently inflamed, in the tonsillar fossa between the pillars of
fauces (2).
b. Lingual tonsil, made by the lingual follicules, which are collections of lymphoid
tissue in the mucosa of the pharyngeal part of the tongue posterior to the terminal
sulcus.
c. Pharyngeal tonsil, adenoid, in the nasopharynx.
d. Tubal tonsils, nasopharynx, close to the opening of each auditory tube (2).

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The Teeth
Hard conical structures set in the alveoli of the upper and lower jaws, used in mastication and
assisting in articulation, forming an arch that separates the vestibule from the oral cavity proper.
Humans usually have 20 primary teeth (also called deciduous, baby, or milk teeth) and 32
permanent teeth, which means 2 sets of teeth or Diphyodont
Among primary teeth, 10 are found in the (upper) maxilla and the other 10 in the (lower)
mandible.
In the primary set of teeth, there are two types of incisors, centrals and laterals, and two types of
molars, first and second. All primary teeth exofoliate and are replaced with permanent
counterparts except for molars, which are replaced by permanent premolars.
Among permanent teeth, 16 are found in the maxilla with the other 16 in the mandible, lying
closely to each other with no space between them (ideally!) (If there is space between the teeth
it's called: Diastema).

Humans have heterodont dentition, which means the teeth have 4 different shapes (types) for
different functions:

- Incisors: chisel shaped, for biting (cutting edge), has a tubercle on the oral side and a
single conical tapering root; the maxillary incisors are more broad
- Canines: firmly rooted & long, for tearing and gripping. Got an acute angle, a chewing
point and a long, slightly flattened conical root
- Premolars: broad crown, for grinding & crushing, has 2 tubercles or cusps on the
occlusal surface of crown
o Maxillary 1st premolar got divided roots (furrowed)
o Mandibular premolars, and 2nd maxillary premolar got simple roots
- Molars: broad surface, for chewing. Got 4 tubercles on the chewing surface
o Maxillary molars got 2 vestibular root and 1 oral
o Mandibular molars got 1 vestibular root and 1 oral

The teeth form 2 arcades or arches, the upper teeth arch (maxillary) is ellipsoid or half eclipse
shaped, while the lower (Mandibular) is parabola shaped

Each tooth has different surfaces:

- Masticatory surface (occlusal surface): contacts the teeth of the opposing dental arcade,
- Vestibular surface: facing the lips or cheeks
- Lingual or Palatal surface: the inner surface of teeth, facing the oral cavity proper
- Approximal surface: facing the adjacent tooth, subdivided into,
o Mesial surface: facing anteriorly or medially
o Distal surface: facing posteriorly or laterally

The normal healthy bite (Dentition) is called the Scissors bite (Psaliodontia, in which the teeth
don’t meet exactly, but the maxillary incisors overlap over the Mandibular incisors)

The lingual nerve passes close to the 3rd Mandibular molar

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Parts of the tooth:

- Crown: the portion of the tooth covered by the hard acelluar enamel, which is the hardest
substance of the human body, made of enamel prisms (ground substance 90%
hydroxyapatite and 6-8% calcium carbonate, calcium fluoride, and magnesium carbonate,
the remainder comprising an organic matrix of protein and glycoprotein)
We can distinguish:
o Anatomical crown: the whole crown of the tooth covered by the enamel
o Clinical crown: the portion of the crown visible above the gingiva in the oral
cavity

- Dentine: the avascular ivory forming mass of the tooth, under the enamel. About 20% is
organic matrix, mostly collagen, with some elastin and mucopolysaccharide; the
inorganic fraction (70%) is mainly hydroxyapatite, with some carbonate, magnesium, and
fluoride
On its inner surface we find odontoblasts, sending projections called Odontoblastic
processes (Tomes fibers) into the dental canaliculi, which extend up to the dentinoenamel
or cementodentinal junction

- Cementum: bonelike mineralized tissue covering the dentine of the root and neck of a
tooth that serves to anchor the fibers of the periodontal ligament

- Pulp cavity: contains loose connective tissue, blood vessels and nerves known as Dental
pulp, subdivided into:
o Pulp cavity of the crown: the space within the crown of a tooth
o Root canal: the chamber of the dental pulp lying within the root portion of a tooth
o Apical foramen: the opening at the apex of the root of a tooth that gives passage
to the nerve and blood vessels

- Neck of tooth (Collum): the slightly constricted part, between the crown and the root

- Root: that part of a tooth below the neck, covered by cementum rather than enamel, and
attached by the periodontal ligament to the alveolar bone

** Note: The histological structure of the teeth should be studied with more details from the lectures provided by the
department, or from the atlases of histology recommended by the department, as well as the embryological
development and eruption of the teeth that can be found in the histological manual of the department or in the
Thieme Internal organ book, especially for dental students.

Supporting structures of teeth:

- Periodontal ligament: springy suspension of teeth in the bony alveoli, perforation fibers
of Sharpey's (collagen) are found anchored in the cementum and reaching he periostieum
of the bony alveolus, permits slight mobility
- Periodontium: periodontal ligament + cement + gingiva + alveolus
- Tooth sockets (Alveoli dentalis): small pockets of the maxillary or mandibular alveolar
processes housing the teeth, separated by the interalveolar septa
- Interraidicular septa: separates the different roots of teeth where there is more than 1
root

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Teeth formula:

4 groups of teeth in 2 arches, mirror image of each side of median plane

From middle line to the distal end we have:
- 2 incisors, 1 canine, 2 premolars, 3 molars (Third molars are commonly called "Wisdom teeth"
and may never erupt into the mouth or form at all)

This gives a formula of 2123 on each quadrant of mouth according to this table:

FDI Two-Digit Notation

Permanent teeth

upper right upper left

18 17 16 15 14 13 12 11 21 22 23 24 25 26 27 28

48 47 46 45 44 43 42 41 31 32 33 34 35 36 37 38

lower right lower left

Examples:
- "13" = permanent upper right canine
- "32" = permanent lower left lateral incisor

Orientation in the oral cavity:

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Arterial supply of teeth:

1) Lower jaw: Inferior alveolar artery (branch of maxillary) inside the Mandibular canal
2) Upper jaw: anastomosis between,
a. Superior-Posterior alveolar artery (branch of maxillary) through the maxillary
tuberosity to supply the posterior teeth and gums
b. Superior-Anterior alveolar artery (branch of infraorbital) supplies the anterior
teeth and gums

Nerve supply of teeth:

1) Lower jaw: Mandibular branch of the trigeminal nerve (CNV3): Inferior alveolar
(Dental) nerve & plexus
2) Upper jaw: the superior dental plexus formed by the Maxillary branch of the trigeminal
nerve (CNV2) and the Infraorbital nerve
a. 876 teeth by the Posterior superior alveolar (Maxillary branch)
b. 543 teeth by the Middle superior alveolar (Infraorbital branch)
c. 21 teeth by the Anterior superior alveolar (Infraorbital branch)

Deciduous Teeth features:

- 20 in number
- 2 incisros, 1 canine, no premolars and 2 molars
- Smaller size, globular crown, short and wide
- Their shapes are more stable
- Bluish enamel
- Sharp border between enamel and cementum
- Wide pulp chamber and root canals
- Thin dentin, thick enamel
- Serious abrasion

Order of Eruption:

A) Primary dentition (deciduous):

1) Incisors (1st then 2nd)
2) 1st primary molars
3) Canine teeth
4) 2nd primary molar
B) Permanent dentition:
1) 1st molar
2) Incisors (1st then 2nd)
3) 1st premolars
4) Canine teeth, 2nd premolar
5) 2nd molar
6) 3rd molar

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The Salivary glands

- Parotid gland
- Submandibular gland
- Sublingual gland
- Accessory minor glands scattered over palate, lips, cheeks and tongue

Secrete the tasteless, clear, odorless Saliva, which has functions in:
1) Keep mucous membrane of mouth moist (intrinsic mouth wash), which is the main
role of the minor salivary glands
2) Lubrication of food & beginning of starch digestion
3) Prevention of teeth decay

Parotid gland: pure serous (check drawing of the Parotid nest)

Largest, enclosed with a tough fascial capsule, the parotid sheath (part of the investing
layer of the cervical fascia). Has an irregular shape parotid bed or nest, in which the
gland lays anterioinferioly to the external acoustic meatus, behind the ramus of the
mandible and in front of the styloid process
Between the lobes there is numerous fat that increase the flexibility and accommodates
the gland to the movement of the mandible
The parotid duct of Stensen passes horizontally and at the anterior border of the messeter
muscle it pierces the buccinator muscle and opens behind the 2nd maxillary molar into the
oral cavity
The accessory parotid gland is an occasional islet of parotid tissue separate from the mass
of the primary gland, lying anteriorly just above the commencement of the parotid duct

** Structures embedded within the gland:

o Parotid plexus of fascial nerve branches
o Retromandibular vein
o External carotid artery and branches (supply the gland also)
o Auriculotemporal nerve (of CN-V3)
o Parotid lymph nodes

Submandibular gland: mostly serous

Found along the body of mandible. The duct is ~5cm long and arises between the
mylohyoid and hyoglossus muscles, passing from lateral to medial, opening on a
sublingual papilla, found both sides lateral to the lingual frenulum
Supplied by the submental artery/vein

Sublingual gland: mostly mucous

The smallest and most deep gland, almond shaped, lying in the floor of the mouth
between the mandible and the Genioglossus muscle. Both glands unite to form a
horseshoe shape under the lingual frenulum. It has many small ducts that open to the
mouth
Supplied by the Sublingual artery (branch of lingual artery) and the submental artery
(branch of fascial artery)

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Borders of the Parotid nest (Nidus parotideus):

- Anterior:
Masseter muscle
Ramus of the mandible
Medial pterygoid muscle
- Posterior:
Sternocleidomastoid
Posterior belly of the digastric
- Medial:
Stylohyoid muscle
Stylopharyngeus muscle
Styloglossus muscle

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The Pharynx
The pharynx is the continuation of the GI tract after the oral cavity. It’s a fibromuscular tube that
is used as a pathway for both food and air.
The Pharynx is divided to 3 parts:
- An upper Nasopharynx that receives the posterior openings of the nasal cavity,
the 2 Choana.
- Middle Oropharynx, behind the oral cavity (after the isthmus of fauces)
- A lower Laryngopharynx, behind the Larynx.

The Pharynx is 15cm and it extends from the base of the skull down to the lower border of the
Cricoid cartilage anteriorly, and to the lower border of C-6 posteriorly, from this point the
pharynx becomes the Esophagus

The Pharyngobasilar fascia:

Is the fibrous coat of the pharyngeal wall situated between the mucous and muscular
coats; it is attached above to the basilar part of the occipital bone, and the petrous part of
the temporal bone. This layer and the mucosa which lines it forms the wall of the non-
muscular pharynx (pharyngeal vault) above the superior pharyngeal constrictor muscle
(so basically the whole pharynx is hanging down from the base of skull by this fascia)

A) The Nasopharynx (Epipharnx):

This part is located above the soft palate, and to it the Choanae (also known as internal
nares) opens. The roof and the posterior walls are formed by the Sphenoid bone and the
basilar part of the Occipital bone. In the mucous membrane we can find the "Pharyngeal
tonsils".

On the lateral wall of the Nasopharynx we find the "Orifice for the auditory tube"
("Eustachian tube"), above this orifice we find the "Torus Tubarius" a small ridge caused
by the projection of the cartilaginous part of the tube. Under this Torus, and posteriorly,
we find the "Salpingopharyngeal fold" that covers a muscle with the same name which is
in charge of opening the tube during chewing. Anterior to the Torus, we can find a small
fold called "Salpingopalatal fold". Under the hiatus for the Eustachian tube we fin the so
called small "Torus Levatorius" made by the underlying Levator veli palatini muscle

Behind the orifice of the auditory tube, we can find the Tubarian tonsils, and above the
Torus we can see a "pharyngeal recess"

Passavant Ridge: a prominence on the posterior wall of the nasopharynx formed by

contraction of the superior constrictor muscle of the pharynx during swallowing

B) The Oropharynx (Mesopharynx):

To this area the oral cavity opens via the "Orophryngeal Isthmus" or "Isthmus of
Fauces". The superior border of this part is the soft palate, and the inferior border is the
base of the tongue and the superior border of the Epiglottis.
The Palatine tonsils are located within the Oropharynx in an area called the "Tonsillar
bed" located between the palatine arches: the "Palatoglossal arch" anteriorly and the
"palatopharyngeal arch" posteriorly.

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C) Laryngopharynx (Hypopharynx):

This part runs from the superior border of the epiglottis till the inferior border of the
cricoid cartilage, and from this area, the Pharynx continues as the esophagus.
The Laryngopharynx is in contact with the larynx by the "Inlet or Aditus of the larynx",
and at the sides of this inlet we find the bilateral Piriform recess which is a depression of
the laryngoharengeal cavity. Between these Piriform recess and the inlet of the larynx we
find the "Aryepiglottic fold"

Muscles of the pharynx:

A) The Constrictors of pharynx:

The constrictors are organized in a way that the superior constrictors are the innermost
and the inferior constrictors are the outermost (like the roof tiles, but opposite). Their job
is to involuntary propelling the food downward towards the esophagus.
Origin of the 3 Constrictors of Pharynx:

1) Superior constrictor:
- Pterygopharyngeal part (Pterygoid process)
- Buccopharyngeal part (Pterygomandibular raphe)
- Mylopharyngeal part (Mylohyoid line of mandible)
- Glossopharyngeal part (root of tongue)

2) Middle constrictor:
- Chondropharyngeal part (Greater & lesser horns of Hyoid bone)
- Ceratopharyngeal part (Stylohyoid ligament)

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3) Inferior constrictor:
- Thyropharyngeal part (Thyroid cartilage)
- Cricopharyngeal part (Cricoid cartilage): has a sphincteric function for
the esophagus, forming the upper esophageal sphincter (UES) allowing
some voluntary control of eructation and reflux. Can be a separate muscle

** All the constrictors of pharynx insert posteriorly in the midline on the

Median raphe of pharynx and the pharyngeal tubercle

B) Elevators of pharynx:
The pharynx has 3 important intrinsic muscles that lay deep to the constrictors that their
job is to elevate the Pharynx and the Larynx during speaking or swallowing

5) Stylopharyngeus muscle:
o origin: styloid process
o Insertion: the anterior and posterior parts of the thyroid cartilage

6) Palatopharyngeus muscle:
o origin: Hard palate and the palatine aponeurosis
o Insertion: posterior border of the Thyroid cartilage lamina

7) Salpingopharyngeal muscle:
o origin: cartilaginous part of the auditory tube
o Insertion: Palatopharyngeus muscle

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Peripharyngeal space
See the discussion of the peripharyngeal space (retrovisceral, retropharyngeal, danger &
parapharyngeal spaces in the neck fascia section)

Pharyngeal mucosa:

The nasal portion is covered by the nasal respiratory epithelium, and the oral and
laryngeal portion has the same epithelium as the oral cavity (Stratified squamous non-
keratinized).
Mucous glands, the pharyngeal glands, provide the lubricating mucous. The subepithelial
connective tissue contains abundant elastic fibers, allowing the pharyngeal wall to stretch
and recoil. In the laryngeal portion at the transition to the esophagus, the mucosa of the
anterior and posterior wall of the pharynx is separated from the skeleton of the larynx and
the cervical spinal column by a venous plexus.
The buccopharyngeal fascia: the fascia that covers the muscular layer of the pharynx
and is continued forward onto the buccinator muscle

Arterial supply of the pharynx:

o The upper parts of the pharynx receive their blood supply from branches of the facial and
maxillary arteries
o The ascending pharyngeal artery arises from the external carotid artery to supply the
lower pharynx and larynx
o The superior thyroid artery arises from the external carotid artery to give the pharyngeal
branches that supply the lowest part of the pharynx and part of the esophagus
o Venous drainage: into the pharyngeal plexus, posterior to the pharynx

Innervation of the pharynx:

o Pharyngeal plexus: branches of Glossopharyngeal, Vagus and Sympathetic nerves

o Motor supply: cranial part of accessory n. which indirectly via the Vagus, branch to
pharyngeal plexus supplies all muscles of pharynx except Stylopharyngeus, superior
constrictor of pharynx & the upper 1/2 of the middle constrictor of pharynx! (Supplied by
glossopharyngeal n.)
o Sensory supply: mucous membrane of nasopharynx is supplied mainly by maxillary
nerve (CN-V2) via Pharyngeal branch of sphenopalatine ganglion.
The Oropharynx mainly by glossopharyngeal n. (Posterior 3rd of tongue and
Oropharynx).
Around the laryngeal inlet,
Laryngopharynx: internal
laryngeal Branch of Vagus,
(branch of superior laryngeal)

Lymphatic drainage of the pharynx:

o Retropharyngeal lymph nodes

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The Esophagus
A muscular tube that is 25cm long, with an average diameter of 2 cm, conveying the food bolus
from the pharynx into the stomach, it consists of three parts: the cervical part, from the cricoid
cartilage to the thoracic inlet; the thoracic part, from the thoracic inlet to the diaphragm; and the
abdominal part, below the diaphragm to the cardiac opening of the stomach.
** The cervical and thoracic parts are fused with the membranous wall of the trachea

The esophageal wall has an internal circular and an external longitudinal layer of muscle, the
Upper 1/3 – striated muscle, middle 1/3 is mixed fibers of smooth and skeletal muscles, lower
1/3 – smooth muscle.
It has also 3 constrictions where adjacent structures produce impressions on it:
- Cervical constriction: at Pharyngo-esophageal junction (C5 level), caused by the
cricoid cartilage (Cricoid angustia). At this point, the Cricopharyngeous part of the
lower constrictor of pharynx muscle forms the Upper Esophageal Sphincter (UES).
- Thoracic (Aortic) constriction: is a compound constriction, 1st crossed by the arch
of aorta then by the left main bronchus (in some sources, the Broncho-aortic
angustia)
- Diaphragmatic constriction: at the esophageal hiatus in the diaphragm, Th-10 level,
formed by the Right Crus of diaphragm (although the esophagus is on the left side!)
and the phrenico-esophageal ligament attach the esophagus to diaphragm at hiatus.
The Lower Esophageal Sphincter (LES) is formed here by the right crus and the
ligament, and this sphincter is very important for preventing the acidic contents of
the stomach to be regurgitated back into the esophagus (Gastro-esophageal reflux)

** Laimer trigone: a triangular (or V-shaped) area on the posterior aspect of the
proximal esophagus, with its apex directed inferiorly in the midline and the
cricopharyngeous muscle forming its base, which is an area of weakness due to the
absence of outer longitudinal muscle layer of the esophagus. It's a potential site of
herniation of pharyngeal or esophageal mucosa known as Zenker Diverticulum
(Pharyngo-esophageal diverticulum)

Following the curve of vertebral column as it descends through neck and posterior mediastinum
in a slight arch towards the right but reaching the left side at the diaphragm, contacting the Left
atrium of the heart posteriorly in the middle of the thorax.

After it pierces the diaphragm through the esophageal hiatus, it has the abdominal part which is
1.5cm long (that has a groove on the posterior surface of the liver). It terminates entering
stomach at the Cardial orifice (Cardia) (Esophago-gastric junction), Left To midline, at the level
of the 7th costal cartilage or Th-11 vertebral body
** weakness in the connective tissue of the esophageal hiatus of the diaphragm can result
in Hiatal hernia, in which the abdominal part of the esophagus as well as parts of the
stomach protrude into the thoracic cavity

Z-line: where the mucosa abruptly changes from Esophageal (Stratified non-keratinized
squamous) to Gastric (Simple columnar, glandular) at the cardia

The Arterial supply of the esophagus:

- Esophageal branch of Inferior thyroidal artery (cervical part)
- Esophageal branch of Left & Right bronchial arteries (thoracic part)

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- Esophageal branches of Thoracic aorta (segmental) (thoracic part)

- L. Gastric art. (From Celiac trunk) (Abdominal part)
- L. Inf. Phrenic art. (Abdominal part)

Venous drainage is from the sub-mucosal veins as part of the Porto-Caval anastomosis
(See the liver for more details):
- into the Portal system through L. Gastric v. of stomach (coronary vein)
- into the Systemic venous system (SVC by the Azygos and hemiazygos veins)
through the Esophageal veins

Lymphatic drainage:
- L. gastric lymph nodes into celiac nymph nodes.
- Inferior Deep cervical lymph nodes
- Para-tracheal lymph nodes
- Posterior mediastinal & Intercostal lymph nodes

Innervation:
It has an esophageal nerve plexus, formed by the 2 Vagal nerves (running parallel) as the
Parasympathetic portion + Thoracic sympathetic trunks via the greater Splanchnic nerve and the
peri-arterial plexus around L. gastric and inf. Phrenic arteries.
The parasympathetic nerve supply comes from the nucleus ambiguus and dorsal motor nucleus
of the vagus nerve and provides motor innervation to the esophageal muscular coat and
secretomotor innervation to the
glands. The sympathetic nerve
supply comes from the cervical and
the thoracic sympathetic chain
(spinal segments T1–T10) and
regulates blood vessel constriction,
esophageal sphincters contractions,
relaxation of the muscular wall,
and increases in glandular and
peristaltic activity.
The thin nerve fibers and numerous
ganglia of the intramural myenteric
and the submucosal plexi provide
the intrinsic innervation of the
esophagus. The ganglia that lie
between the longitudinal and the
circular layers of the tunica
muscularis form the myenteric or
Auerbach's plexus, whereas those
that lie in the submucosa form the
submucous or Meissner's plexus.
Auerbach's plexus regulates
contraction of the outer muscle
layers, whereas Meissner's plexus
regulates secretion and the
peristaltic contractions of the
muscularis mucosae.

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The Stomach
A J-shaped (Usually) hollow organ, but its shape varies and depends on the body eating habitus
or position. (Can be Elongated or Transverse shaped also)
In supine position, it rests on the so called Stomach bed, made of the following organs:
Pancreas, spleen, L. kidney, L. suprarenal gland, transverse colon and Mesocolon

Totally intra-peritoneal organ, located in L. Hypochondrium and Epigastric regions of the

Abdomen, and as a J-shaped organ it has 2 margins or Curvatures:
- Lesser curvature: forms the shorter concave border of stomach, the Angular
Incisure (notch) is the sharper indentation at the 2/3 distance along the lesser
curvature, that indicates the junction of the body with pylorus. The Hepatogastric
ligament is a very thin duplication of the peritoneum (Part of the Lesser omentum)
reaches the lesser curvature.
- Greater curvature: forms the longer convex border of stomach, less fixed part, or
not at all. 2 double Layers of the peritoneum (4 total layers) meet each other at
greater curvature forming together the Greater Omentum (and the Gastrocolic
ligament fused together with 2 layers of the Transverse Mesocolon, so total 6
layers).

Parts of the stomach:

- Cardia: is the funnel shaped part surrounding cardial orifice, left side of Th-11
vertebra, related to ribs (7th, 2cm left of midline). It’s the most fixed point of
stomach, attached to the diaphragm by the Gastrophrenic ligament.
- Fundus: is the dilated superior part related to left dome of diaphragm, it can reach
the level of the 5th IC space. The Cardial notch is a deep incisure on the greater
curvature between the Esophagus and the Fundus, forming an acute angle of His,
which functions as an additional valve besides the LES that prevents reflux of
gastric contents back into the esophagus. It can be dilated by different substances
(gas, H2O, food) forming the Stomach Bubble. Located in Hypochondrium and
related also to spleen.
- Body: (corpus) major part of the stomach that has the lesser and greater curvatures.
- Pyloric part: is a funnel shaped outflow region of the stomach divided into 2 parts:

o Pyloric Antrum: wide part, leads into the

o Pyloric Canal: narrow part, that has the pylorus at its end

The Pylorus: is a distal sphincteric region of the pyloric part of stomach,

which is marked by the thickening of the circular layer of smooth muscle, named
the pyloric sphincter muscle: controls the discharge of stomach's contents through
pyloric orifice into duodenum.

** It is the Second most fixed point of stomach, Right side of L-1 vertebra, 1.5cm
from Midline (Trans-pyloric line)

The Interior of stomach:

Reddish brown gastric mucosa, pink pylorus,
When contracted, gastric mucosa is thrown into longitudinal ridges called Gastric folds or
Gastric Rugae, and when stomach is dilated folds are decreased

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A Gastric canal (furrow) (food canal) (Magan Strasse) forms temporarily during swallowing
between the longitudinal gastric folds of mucosa along lesser curvature to direct the food into
pylorus. The folds become irregular at the fundic region of stomach
The muscular layer of the stomach consists of bundles of smooth muscle and divided into:
- Inner circular layer
- Outer longitudinal layer
- Innermost 3rd Oblique layer (from cardia to the angular notch only)

Ligaments of the stomach (Duplications of peritoneum):

- Hepatogastric ligament: from the liver (fissure of ligamentum Venosum) into the
lesser curvature, part of the Lesser Omentum. Contains the L. and R. gastric art. /v.
- Gastrocolic ligament: from the greater omentum (hanging from the greater
curvature) to the transverse Mesocolon, fusing with it forming the 6 layers
Gastrocolic ligament. Contains the anastomosis between the L. and R.
Gastroepiploic arteries
- Gastrosplenic ligament: the continuation of the Gastrocolic ligament on the left
side. Passes to the spleen and continues further to the left as the Phrenico-splenic
ligament. Contains the short gastric arteries and the beginning of L. Gastroepiploic
art.

Arterial Supply of stomach:

Rich arterial supply arising from celiac trunk and its branches:

- Left Gastric art. (Branch of celiac trunk): ascends to esophageal hiatus in a semi-
intraperitoneal position first giving cardial branches, forming a fold of peritoneum
called Gastropancreatic fold, and then descends along lesser curvature to
anastomose with R. gastric art.
- Right gastric art. (Branch of proper hepatic art. or common hepatic art.): runs along
the lesser curvature of stomach to anastomose with L. gastric art.
- Posterior gastric art. (Branch of Splenic art.): behind the stomach, ascends along the
posterior wall of the Omental bursa to enter the Gastrophrenic ligament. (for the
posterior wall of stomach + cardia)
- Short gastric arteries (4-5 branches of splenic art. at the hilum of spleen): passes
between the layers of Gastrosplenic ligament to the fundus of stomach
- Left Gastro-omental (Epiploic) art. (Branch of splenic art. at the hilum of spleen):
passes into the greater omentum (or the Gastrocolic lig.) to the stomach, then along
the greater curvature to anastomose with R. gastro-omental (Epiploic) art.
- Right Gastro-omental (Epiploic) art. (Branch of Gastro-duodenal art.): passes into
the greater omentum, behind duodenum along the greater curvature of the stomach
to anastomose with the Left Gastro-omental (Epiploic) art.

Venous Drainage of stomach:

- Left Gastric vein: (Coronary v. of stomach): made by esophageal branches and

veins from surface of cardia of stomach. Runs in the lesser omentum and drains into
portal vein. (participates in the porto-caval anastomosis)
- R. gastric vein: receives veins from both surfaces of upper portion of stomach, runs
along the lesser curvature and drains into portal vein.
- Short gastric veins: drain Fundus + L. portion of stomach drain into splenic vein.

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- L. Gastroepiploic vein: runs with the artery empties into splenic v.

- R. Gastroepiploic vein: runs with the artery empties into Sup. Mesenteric v.
- Prepyloric vein: ascends over pylorus to the R. gastric v, used to identify the pylorus
by surgeons.

Lymphatic drainage of stomach:

- Lymph from sup 1/3 of stomach: along the R. and L. gastric vessels into Gastric
lymph nodes which goes to Cisterna Chyli
- Lymph from fundus & superior body: along short gastric art. And Left gastroepiploic
artery Pancreatico-splenic lymph nodes
- Lymph from R. 2/3 of inf. 1/3 of stomach: Pyloric & gastroomental lymph nodes
(connected to hepatic lymph nodes, can cause metastasis to liver in case of gastric
cancer)
- Lymph from L. 1/3 of greater curvature Pancreatico-duodenal lymph nodes.

**Note: Lymph from the stomach can also drain into the mediastinal lymph nodes and
then to the Left Supraclavicular Lymph node of Virchow (Signal lymph node), this is
very important clinically, since it can be a sign of metastatic gastric cancer. Another
sign of gastric cancer can be the Sister Mary Joseph's nodule, which is a palpable
lymph node bulging into the umbilicus.

Parasympathetic innervation: from Anterior (L.) / Posterior (R.) Vagal trunks + celiac
plexus
Sympathetic innervation: Th6 – Th9 celiac plexus through greater splanchnic nerves

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The Small intestine

About 5 meters long, Consists of Duodenum, Jejunum and Ileum
The primary site for absorption of nutrition from ingested materials, extends from the Pylorus to
the Ileocecal junction, where the ileum joins the cecum

A) Duodenum:

C- Shaped hollow organ surrounding the head of the pancreas, widest but shortest part of the
small intestines (Duodenum means 12 fingers ~25cm). Starts at the Pylorus and ends at the
Duodenojejunal flexure

The duodenojejunal junction: occurs at the level of L2, 2-3 cm left of midline, makes an
acute angle, the duodenojejunal flexure. It’s a fixed point by the Suspensory ligament of Treitz,
which is attached to the crus of the diaphragm and has some skeletal muscle fibers in it (in some
sources, it say its attached to the celiac trunk of the abdominal aorta).

** The superior & inferior duodenal folds cover the superior & inferior duodenal recesses
respectively
** The paraduodenal fold a sickle-shaped fold of peritoneum sometimes found arching between
the left side of the duodenojejunal flexure and the medial border of the left kidney; it's right free
edge contains the ascending branch of the left colic artery and inferior mesenteric vein; forms
anterior boundary of the paraduodenal recess.
They are typical places of internal herniation (Treitz Hernias)

The duodenum consists of 4 parts:

1) Superior Horizontal 1st part:

Short (~5cm), lies anterolateral to the body of L1 vertebra, continuous at the superior
duodenal flexure with the 2nd descending part of the duodenum. Has a dilated portion
called duodenal Ampulla in which the pylorus connects (Called duodenal cap or Bulb on
radiographs) it’s a mobile part and attaches the Hepatoduodenal ligament (part of the
lesser omentum). This part of the duodenum is Intraperitoneal
Relations:
- Anterior: Peritoneum, gallbladder, caudate lobe of the liver
- Posterior: Common bile duct, gastroduodenal artery, IVC, portal vein
- Inferior: Neck of pancreas
- Superior: Neck of gallbladder, Epiploic foramen

2) Descending 2nd part:

7-10 cm descends along the R. side of L1-L3 vertebrae until the inferior duodenal flexure,
parallel to IVC, contains the junction the foregut with midgut.
The common bile duct and the main pancreatic duct unite to form Hepatopancreatic
ampulla, which is a dilation that opens into the posteriomedial wall of this part of
duodenum as Vater's papilla (major duodenal papilla), guarded by the muscular
sphincter of Oddi, located 10 cm from the pylorus.
Another minor duodenal papilla (of schner or Santorini) is located 2-3 cm proximal to
Vater's; it's the opening of the accessory pancreatic duct of Santorini
This part of the duodenum is totally Retroperitoneal (Secondary)

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Relations:
- Anterior: Transverse colon, Mesocolon, coils of small intestine
- Posterior: Hilum of R. kidney, renal vessels, Ureter
- Medial: head of pancreas

3) Inferior Horizontal 3rd part:

6-8 cm, crosses L3 vertebra to the left side transversally, passing over IVC, aorta and L3
vertebral body, crossed anteriorly by the SMA/SMV and the root of mesentery
Together with the left renal vein & uncinate process, this part of the duodenum is located
between the abdominal aorta & SMA.
(In extreme cases, if we eat too much, the SMA & Aorta can compress the filled 3rd part
of the duodenum and passage of the food will stop causing Ileus).
This part of duodenum is Retroperitoneal (secondary).
Relations:
- Anterior: SMA, SMV, coils of small intestines
- Posterior: R. Psoas major, IVC, Aorta, R. Ureter
- Superior: Head of pancreas + Uncinate process + SMA/ SMV

4) Ascending 4th part:

~5cm, begins at the L. side L3 level and ascends superiorly until L2, reaching the inferior
border of the body of the pancreas, then curves again to join the jejunum, becoming again
Intraperitoneal, forming the Duodenojejunal flexure (junction), this part of duodenum is
Retroperitoneal (secondary)
Relations:
- Anterior: Beginning of root of mesentery, coils of jejunum
- Posterior: L. Psoas major
- Medially: head of pancreas
- Superior: body of pancreas

Arterial supply of the duodenum:

Supplied by the celiac trunk and Superior mesenteric artery

- Superior Pancreaticoduodenal artery (branch of Gastroduodenal): divides

into Anterior & Posterior arteries that descend around the pancreatic head,
anastomosing with the branches of the Inferior PD artery of SMA. Supplies
the Proximal duodenum and the Superior part of head pancreas

The duodenum develops from both the foregut & midgut, which are
supplied by the celiac trunk and SMA respectively
The anastomosis between the Superior & Inferior Pancreaticoduodenal
arteries around the head of pancreases and duodenum is the so called First
Riolan arch (or the Minor/Lesser Riolan anastomosis), which marks the
border between foregut and midgut embryologicaly
** See surgical significance of the Pancreaticoduodenal arteries in the
description of pancreas

- Gastroduodenal artery (branch of the common hepatic artery): descends

posteriorly to the gastroduodenal junction (pylorus) and supplies the stomach,
pancreas, 1st part of duodenum and distal part of the bile duct. Gives also the
Supraduodenal artery

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- Inferior Pancreaticoduodenal artery (branch of the superior mesenteric

artery): divides into Anterior & Posterior arteries that ascend on each side of
the pancreatic head, anastomosing with the similar branches from the superior
PD artery. Supplies the Distal parts of duodenum and the inferior part of head
of pancreas

Venous drainage of the duodenum: by the Pancreaticoduodenal veins into the SMV

Lymphatics: - Anterior lymph vessels into Pancreaticoduodenal and pyloric lymph nodes
- Posterior lymph vessels into the SMLN (superior mesenteric lymph nodes)

Innervation: - Parasympathetic: Vagus

- Sympathetic: Lesser/Greater Splanchnic nerves

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B) Jejunum & Ileum:

The jejunum is the second part of the small intestine that begins at the Duodenojejunal
flexure located intraperitonealy. Makes about 2/5 of the length of small intestines
Its wider, emptier and thicker walled than the ileum, most of it lays in the upper left quadrant of
the abdominal cavity. Grossly with the naked eye, the plica circularis can be seen (circular folds
of Kerckring) in the lumen. Microscopically it contains no Peyer patches!
It has more translucent windows between the vessels in its mesentery and less fat, less prominent
arterial arcades compared with the ileum, but has longer Vasa recta.

The ileum is longer than the jejunum, 3/5 of the small intestines, and occupies the false pelvis
in the Right lower quadrant of the abdomen, it is darker, has more vertical loops than the
jejunum. Histologicaly, it contains Peyer patches (on the anti-mesenterial side, bulging into the
lumen in some cases), shorter plica circularis, shorter vasa recta, but more mesenteric fat and
more prominent arcades compared with jejunum

* Meckel's diverticulum: the remains of the yolk stalk of the embryo, which, when
persisting abnormally as a blind sac or pouch in the adult, is located 60-90 cm orally from
the Ileocecal junction; it may be free in the abdominal cavity or attached to the umbilicus.
Inside we can find Ileal tissue, with frequents islets of gastric or pancreatic tissues!

The Root of mesentery:

~15 cm directed obliquely, inferiorly and to the right extends from Duodenojejunal
flexure on the left side of L2 to the Ileocecal junction in the right iliac fossa, at the level
of right sacroiliac joint
Crosses part 2 & 3 of duodenum, abdominal aorta, IVC, R. Ureter, R. Psoas major, R.
Testicular artery/ ovarian artery and contains the superior mesenteric vessels, lymphatics
and nerves

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Arterial supply of Jejunum & Ileum:

Superior mesenteric artery, which arises at the level of L1, 1cm under the celiac trunk,
and goes between the head of pancreas, uncinate process and the inferior horizontal part
of duodenum into the root of mesentery to give 15-18 Jejunal & Ileal (4-5 Jejunal, 11-13
ileac) branches to the intestines
Those branches anastomose together forming the Intestinal arterial arcades, which
become more prominent towards the terminal ileum. From the arcades, the straight
branches or Arteria recta or Vasa recta reach the intestines as terminal branches (not to
be confused with the vasa recta in the kidney)

Venous drainage is by the superior mesenteric vein, which ends behind the neck of pancreas
to join the splenic vein to form the portal vein

Lymphatics:
- Juxta-intestinal lymph nodes: close to the intestinal wall
- Mesenteric lymph nodes: among the arterial arcades
- Superior central nodes: along the proximal part of the SMA
- they drain into the celiac lymph nodes then into Cisterna Chyli and thoracic
duct

Innervation:
- Sympathetic: Th8-Th10 through the sympathetic trunk and lesser/greater
Splanchnic nerves, postganglionic fibers are from the superior mesenteric
ganglia
- Parasympathetic: Vagal trunks (Myentetic & Submucosal plexuses)

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The Large Intestine

The site of reabsoroption of undigested food, water and electrolytes and production of feces
1.5 – 1.8 meter long, composed of:
- Cecum
- Appendix
- Colon (3 parts: Ascending, Transverse, Descending)
- Sigmoid
- Rectum
- Anal canal

The cecum colon and sigma can be distinguished from the small intestines by unique features:

a) Omental appendices: small, sub-peritoneal fatty appendages

b) Teniae coli: three bands in which the longitudinal muscular fibers of the large intestine,
except the rectum & anal canal, are collected
a. Mesocolic: to which transverse and sigmoidal mesocolons attach (mesentery)
b. Omental: site of adhesion of the greater omentum to the transverse colon
c. Libera (free): opposite to the Mesocolic teniae, no attachment

This nomenclature is used for the teniae of the transverse colon, in the case of the
ascending & descending colons, the teniae change position due to the right and left colic
flexure:
- Mesocolic tenia becomes the Posteriomedial tenia
- Free tenia becomes the Anterior tenia
- Omental tenia becomes the Posterolateral tenia

** The omental tenia (the posterolateral tenia) is thin and almost not visible on the
ascending & descending colons, because there is no greater omentum adhered there.
On the sigmoid colon it totally disappears, therefore we can say that the sigmoid
colon has 2 teniae only.

c) Haustra: sacculations of the wall of the colon between the teniae, in the interior aspect of
the wall, between the sacculations, the semilunar folds of the colon are produced.
d) Greater caliber: not totally correct and reliable, because if the small intestines are filled
with food or blocked due to some sort of Ileus, they can have almost the same caliber as
the large colon

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Cecum & Appendix:

Cecum is the 1st part of the Large intestine. It’s a blind intestinal pouch, 7.5cm in length and
width, located in the Right lower quadrant, in the iliac fossa. It has no mesentery and considered
as a Semi-intraperitoneal organ that is bound to the lateral abdominal walls by cecal folds.

- Ileocecal junction:
Terminal ileum enters the cecum and partly invaginate in it, producing Ileocolic lips
(superior & Inferior) at the ileac orifice, which forms the Ileac papilla
The folds meet laterally to form Frenula (ridges) (only seen in cadavers) & Ileocecal valve
of Bauhin

Around the Ileocecal junction we have to distinguish 2 folds:

- Vascular fold of the cecum: a peritoneal fold that arches over a branch of the Ileocolic
artery and bounds in front a narrow recess, the superior Ileocecal (or Ileocolic) recess
- Bloodless peritoneal fold of Treves or the Ileocecal fold: bounding the inferior Ileocecal
or ileoappendicular fossa
** The Retrocecal recess is found behind the right side of cecum

The Vermiform Appendix is a blind intestinal diverticulum (5-9cm) that contains masses of
lymphoid tissue. It has a variable position, but usually arises from posteriomedial aspect of the
cecum inferiorly to the Ileocecal junction (Retrocecal position)
It has a short triangular mesentery called the Mesoappendix which is attached to the cecum and
proximal part of the appendix
Clinically the appendix can be found by using the McBurney point, which a point located onto
the lateral 1/3 of the line connecting the anterior superior iliac spine with the umbilicus (Monro-
Richter line)

The arterial supply of the cecum and appendix:

By the Ileocolic artery, a terminal branch of the Superior mesenteric artery that has 7 branches:
- 3 branches to the terminal ileum
- 2 branches to the cecum (anterior & posterior cecal)
- 1 branches to the appendix (appendicular artery) that descends in the
mesoappendix
- 1 branch to the ascending colon (Ascending Colic)

Venous drainage is done by

the Ileocecal vein that drains
into SMV

Ileocolic lymph nodes: into

the SMLN

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The Colon

A hollow tube that is 1.5 meter part of the Large intestines that has 4 major parts:

1) Ascending colon:
2nd part of the large intestines, it passes superiorly on right side of abdominal cavity from
cecum until right lobe of liver, where it turns to the left forming the Right Colic (hepatic)
flexure.
Its partly (1/2) Intraperitoneal and (1/2) retroperitoneal (secondary) so it's considered as
Semi-intraperitoneal
Between the lateral aspect of ascending colon and adjacent abdominal wall, lies deep
vertical groove lined with parietal peritoneum Right Paracolic gutter, this recess is
continuous upward with the Subhepatic recess and Morrison's pouch, and downward with
the right side of pelvic cavity (iliac fossa), so it can play a role in infection spread

It has the so called Jackson's membrane, a thin vascular membrane or veil like adhesion,
covering the anterior surface of the ascending colon from the cecum to the right flexure;
it may cause obstruction by kinking of the bowel.

Arterial supply: Ileocolic (Ascending colic), Right Colic + middle colic arteries of
SMA (right colic artery anastomose with right branch of middle colic artery and
ascending colic)
Venous drainage: Ileocolic and right colic veins SMV
Lymphatic drainage: Epicolic + Paracolic LNs + Right colic LNs SMLN

2) Transverse colon:
45 cm long, most mobile part of large intestine. Crosses the abdomen as an arch from
right colic (hepatic) flexure to left colic (splenic) flexure where it bends inferiorly.
The Splenic flexure lies anteriorly to the inferior part of left kidney; connected to
diaphragm by Phrenicocolic ligament (holds the spleen in place as the Sustentaculum
Lienis forming the splenic nest)
The mesentery of transverse colon loops downward as the transverse mesocolon. The
root of transverse mesocolon lies along inferior border of pancreas and continues with
parietal peritoneum posteriorly. It forms the inferior border of the omental bursa and
fuses with the greater omentum forming the 6 layered Gastrocolic ligament
Being freely movable the transverse colon varies in position, but we can say it's
around L3 vertebral level

Arterial supply: mainly Middle colic artery (right 2/3) (branch of SMA) and Left colic
artery (left 1/3) (branch of IMA)

** The left colic artery (of IMA) anastomosis with middle colic artery (of SMA) to form
the 2nd Riolan anastomosis or (Major/Greater) arc, around the left colic (splenic)
flexure, which marks the border between midgut and hindgut.

Venous drainage: middle colic vein SMV

Lymphatic drainage: Middle colic lymph nodes into SMLN

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3) Descending colon:
Thinner than the ascending colon, partly intra, Semi-intraperitoneal, as it descends,
passes anterior to lateral border of Left kidney, and has left Paracolic gutter, which is
closed upward by the Phrenicocolic ligament.

Arterial supply: - Left colic artery (branch of IMA)

** The marginal artery of Drummond: an artery formed by anastomosis between the

right and left colic arteries; it passes downward from the left colic flexure to the aboral
(away from the mouth) end of the pelvic colon. The 2nd Riolan arc is a specific part of
this artery

Venous drainage: L. colic veins IMV

Lymphatic drainage: L. Colic lymph nodes – IMLN

4) Sigmoid colon:
S-shaped loop (40 cm) extends from iliac fossa to S3 vertebra
The termination of teniae (15 cm from anus) indicates the Rectosigmoidal junction. It has
a long Mesosigmoidium freely moving. The root of Mesosigmoidium is an inverted-V
shaped, from the Medio-superior to the anterior aspect of the sacrum.
** The Left Ureter + bifurcation of external iliac behind apex of the Mesosigmoidium

Arterial supply: Sigmoidal artery (IMA) with ascending/ descending branches

* The Sudeck point (discussed in the Rectum) is an anastomosis between the
sigmoidal artery and the Superior rectal artery.

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Venous drainage: Sigmoidal vein into IMV

Innervation of the Colon:

- Parasympathetic:
o Vagus nerves (until the 2/3 of the transverse colon)
o Sacral Plexus (1/3 of the transverse colon until anus)
The point where the innervation changes from the Vagus to the
sacral plexus, located between the right 2/3 and left 1/3 of
transverse colon, is called Cannon-Böhm point (also marks the
site of the 2nd Riolan arch)
- Sympathetic:
o Superior hypogastric plexus

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The Rectum
The rectum is a 15-20 cm long S-shaped hollow organ located after the sigmoid colon in the
pelvis. The Rectosigmoidal junction is located anteriorly to the S3 vertebra.
At this point, the teniae of Sigmoid colon spread out to form outer continuous smooth muscle
layer and the omental (Epiploic) appendices & the haustrations disappear.

The rectum follows the shape of sacrum and coccyx Sacral flexure of rectum at first, then it
turns backward to the anterior inferior tip of coccyx, forming a sharp turn Perineal
(Anorectal) flexure (80º), that occurs when the rectum perforates the pelvic diaphragm posterior-
inferiorly, and its very important in the defecation mechanism.

From the outside, in the frontal plane, we can observe 3 sharp lateral flexures of the rectum
(Superior, Intermediate and Inferior) which are formed in relation to internal folding The
transverse rectal folds (Houston valves):
- 2 on left side (Superior and inferior)
- A prominent 1 on the right side (middle one), Kohlrausch's fold (5-6 cm from the
anus)

The Ampulla of rectum: dilated terminal part of rectum below the Kohlrausch's fold, lying
directly superiorly to and supported by Pelvic diaphragm (Levator Ani muscle) and the
Anococcygeal ligament. Receives and holds accumulated feces, and when it full, the sensation of
defecation occurs

The Superior 1/3 of rectum semi-intraperitoneal, Middle 1/3 is Retroperitoneal (Due to its S
shape) and the inferior 1/3 is Infraperitoneal
o In males, the peritoneum reflects on the Urinary Bladder forming Rectovesical
pouch and the Rectovesical septum that is found between fundus of UB and rectum.
It is possible to feel the prostate by digital examination in front and below the
Kohlrausch's fold
o In females, the peritoneum reflects on posterior part of the vaginal fornix forming
the Rectouterine pouch of Douglas. (also below the Kohlrausch's fold, used to reach
the posterior vaginal fornix for gynecological purposes)
o In both sexes, peritoneum reflects around Pararectal fossa, enabling the distention of
rectum.

Relations of the Rectum:

Lies posteriorly against inferior 3 sacral vertebrae and coccyx, Anococcygeal ligament, median
sacral vessels and inferior ends of the sympathetic trunk + sacral plexus
- In males related anteriorly to the fundus of Urinary bladder, terminal ureters, ductus
deferens, seminal glands and prostate.
- In females related anteriorly to the vagina.

Arterial supply:
- Superior rectal artery: branch of IMA, for proximal part of rectum (upper 1/3), forming
the Corpus Cavernosum Recti, or the Anal cushions, which is the internal hemorrhoidal
plexus of rectum. The "functional unit" of the corpus cavernosum recti is a narrow, partly
tortuous, thick-walled artery which terminates, without interposed capillaries, directly
into the hollow spaces which are separated from each other by tough connective tissue
septa. The blood remains arterial and acts as"filler," playing no metabolic role. For this

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reason, bleeding from hemorrhoids is always bright red. It also plays an important role
normally in maintaining anal continence.
- Middle rectal artery: branch of internal iliac artery (hypogastric), for middle/inferior
parts (middle 1/3).
- Inferior rectal artery: branch of internal Pudendal artery, for the Anorectal junction
(lower 1/3).

** The Sudeck critical point/ anastomosis: between superior rectal artery of IMA and
Sigmoidal artery (IMA).
Very important in rectal tumors surgery, when the middle portion of the rectum must be removed
with the preservation of the superior portion and the anal canal (together with the sphincter), we
cut the superior rectal artery above the anastomosis and then the superior part of the rectum that
was preserved can be pulled down towards the anal sphincter (and it will still receive blood
through the anastomosis)

Venous drainage:
- Through the superior, middle, inferior rectal veins.
An anastomosis occurs between portal and systemic veins (IVC) in the wall of anal canal,
the superior rectal vein drains into the portal venous system (IMV) and the middle and
inferior rectal veins drain into the systemic system (Internal Iliac vein) part of the
Porto-caval anastomosis.
o The superior rectal v. drains into the IMV, then to the portal vein and into the
liver
o The middle & inferior rectal veins drain into the internal iliac vein and then into
the IVC
** This is of great clinical significance in the case of the hematogenous metastasis of
tumors of the rectum, if the tumor is located in the upper part, its likely to metastasize
via the portal system to the liver mainly, and if its in the lower part of the rectum, its
more likely to metastasize into the lungs.

- The Submucosal rectal plexus (venous), communicates with:

o Vesicle v. plexus in males
o Uterovaginal v. plexus in females

Has 2 parts:
o Internal venous rectal plexus (deep to Anorectal junction mucosa) also part of the
corpus cavernosa recti, forming vascular prominences formed by clusters of
normally sacculated veins of the superior rectal venous plexus which are fed by
arteriovenous anastomosis that cause their engorgement, and which are usually
found to lie laterally on the left and antero- and posterolaterally on the right side
of the anal canal.
o Subcutaneous external rectal venous plexus (external to the muscular wall of
rectum)

Innervation of rectum:
- Sympathetic: lumbar part of sympathetic trunk + superior hypogastric plexus through
IMA.
- Parasympathetic: pelvic splanchnic nerves.

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The Anal Canal

The 4 cm anal canal is the terminal part of the large intestine that extends from the upper aspect
of the pelvic diaphragm to the anus. The anal canal begins where the rectal Ampulla narrows at
the level of the U shaped sling formed by the puborectalis muscle, and ends at the anus, the
external outlet of the GI tract. The anal canal, surrounded by the internal and external anal
sphincters, descends posteroinferiorly between the Anococcygeal ligament and the perineal body.
The canal is collapsed except during passage of feces. Both sphincters must relax for defecation
to occur.
The internal anal sphincter: is an involuntary sphincter surrounding the superior two
thirds of the anal canal. It's a thickening of the circular smooth muscle layer and is
innervated by parasympathetic fibers that pass through the pelvic splanchnic nerves. The
sphincter is tonically contracted most of the time to prevent leakage of fluid; however it
relaxes in response to the pressure of feces or gas distending the rectal Ampulla,
requiring voluntary contraction of the puborectalis and external anal sphincters if
defecation is not to occur.

The external anal sphincter: is a large voluntary striated muscle sphincter that forms
a broad band on each side of inferior two thirds of the anal canal. It has 3 components:
o Subcutaneous part
o Superficial part
o Deep part
The sphincter blends superiorly with the puborectalis muscle and is supplied mainly by
S4 through the inferior rectal nerve.

** the 2 sphincters are separated by a thin layer of longitudinal smooth muscle cells, a
contribution of the longitudinal layer of the intestinal wall and fans out as the Corrugator
cutis muscle of anus into the perianal skin

In the interior of the anal canal, the superior half of the mucous membrane is characterized by a
series of longitudinal ridges, anal columns of Morgagni. These columns contain the terminal
branches of the superior rectal artery and vein. The Anorectal junction, indicated by the
superior ends of the anal columns, is where the rectum joins the anal canal. At this point the wide
rectal Ampulla narrows as it traverses the pelvic diaphragm. The inferior ends of the anal
columns are joined by delicate crescent-shaped mucosal folds which called the anal valves of
Morgagni. Superior to the valves are small pocket like recesses, anal sinuses. When compressed
by feces, the anal sinuses release mucus that aids in evacuation of feces from the anal canal.

The pectinate line (dentate line, pain line), an inferior comb shaped limit of the anal valves that
indicates the junction of the superior part of the anal canal (derived from hindgut) and the
inferior part (derived from proctodeum). The anal canal above the pectinate line differs from the
part below the line in its arterial supply, innervation, and it's venous and lymphatic drainage.
The mucosa of the anal canal has 3 zones:
1) Zona Columnaris: from the Anorectal junction until the pectinate line, on the
columns, composed of Simple columnar epithelium
2) Zona Hemorrhagica: from the pectinate line until the Hilton white or Anocutaneous
line, made of Stratified squamous non-keratinized epithelium
3) Zona Cutanea: Stratified squamous keratinized non-hairy epithelium, continues
below the anocutaneous line with the normal hairy perianal skin. This sharp turn

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where the squamous epithelium lining the lower anal canal becomes continuous with
the skin of the perineum is called the Anal verge

** The Hilton White line is found at the level of the interval between the subcutaneous part of
the external sphincter and the lower border of the internal sphincter, that’s why it's called also the
intersphincteric groove

** Zona hemorrhagica & Cutanea are called together Anoderm which is the lining of the anal
canal immediately inferior to the pectinate line and extending for about 1.5 cm untill the anal
verge; it is devoid of hair and sebaceous and sweat glands, and so is not true skin, although it is
squamous epithelium; it is pale, smooth, thin, and delicate, and shiny when stretched; it is
especially vulnerable to abrasion (as from rough toilet paper), chemical irritants (soaps), and is
well provided with tactile and nociceptive (pain, itch)

Arterial supply of the anal canal:

1. Superior rectal artery: supplies canal above the pectinate line.
2. 2 Inferior rectal arteries: supply the inferior part of the canal, as well as the
surrounding muscles and perineal skin.
3. Middle rectal arteries: assist with the blood supply to the anal canal by forming
anastomosis with the superior and inferior rectal arteries.

Venous drainage of anal canal:

The internal rectal venous plexus drains in both directions from the level of the pectinate line.
1. Superior to the line, the internal rectal plexus drains chiefly into the superior rectal
vein
2. Inferior to the pectinate line, the internal rectal plexus drains into the inferior rectal
veins
3. The middle rectal veins mainly drain into the muscularis externa of the Ampulla and
form anastomosis with the
superior and inferior rectal veins.

Innervation of the anal canal:

1. Superior to the pectinate line:
inferior hypogastric plexus (SYM
+ PSY). Sensitive to stretching
but not pain and temperature
(that’s why deep hemorrhoids are
not painful)

2. Inferior to the pectinate line:

inferior anal (rectal) nerves,
branches of the pudendal nerve.
Somatic innervation sensitive to
pain, touch and temp.

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The Liver
The largest gland and abdominal organ in the body, 1500g in weight, (about 2.5% of TBW)
Occupies most of the right Hypochondrium and upper epigastrium
It lies deep to the right 7th-11th ribs, position varies a bit during respiration, but if its palpable
under the right rib cage margin, then it's pathologically enlarged.

Has a lot of metabolic functions, detoxification, glycogen storage and bile production.

Surfaces of the liver:

1. Diaphragmatic: Convex (Ant., Sup., and some Post.). Smooth and dome shaped.
- Subphrenic recess: between diaphragm and Anterio-Superior aspect of
diaphragmatic surface of liver. Separated into right and left by the falciform ligament.
- Falciform ligament: extends between the liver and umbilicus.
- Subhepatic recess: the part of the peritoneal cavity between the visceral surface of
the liver and the transverse colon, it is subdivided right and left Subhepatic recesses
o Hepatorenal recess (Right Subhepatic recess or Morrison's pouch): a posterior-
superior extension of the Subhepatic recess, between the right part of visceral
surface and the Right kidney. Fluid draining from the omental bursa flows into
this recess, as it’s the deepest point of the abdomen. It also communicates down
with the right Paracolic gutter, reaching the cecal area, which plays an important
role in spreading infections in the peritoneal cavity

** This surface is covered by peritoneum except at the Bare area of liver (nude area)
where it lies in direct contact with the diaphragm. The bare area is demarcated by
peritoneal reflection from the diaphragm to it as the Anterior (Sup.) and Posterior (Inf.)
layers of the right coronary ligament. These layers meet at:
- Right: forms the Right triangular ligament, and extending over the right kidney
as the Hepatorenal ligament
- Left: forms the Left triangular ligament (near the apex of liver)

The IVC leaves a groove on the liver, in the bare area.

** Directly on the surface of liver, below the peritoneum, we can find the fibrous capsule
of liver of Glisson, a layer of connective tissue ensheathing the outer surface of the liver
and also the hepatic artery, portal vein, and bile ducts as these ramify within the liver

2. Visceral: Covered with peritoneum except the Gall bladder fossa and Porta Hepatica (a
transverse fissure where the Portal vein, Proper hepatic artery, Bile ducts + Lymphatics &
nerve plexuses, enters and exists the liver)
This surface has multiple fissures which form a "H" shape, composed of:
1. Right Saggital fissure: a continuous groove formed anteriorly by the
Gallbladder fossa and posteriorly by the IVC groove. It is located between the
Quadrate, Caudate and right lobes

2. Left Saggital fissure: a continuous groove formed anteriorly by the fissure of

Ligamentum Teres hepatis (round ligament of liver, the remnant of left umbilical
vein) and posteriorly by the Fissure of ligamentum Venosum (remnant of the
Ductus Venosus Arantii)

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** The omental tuberosity of liver is an eminence on the visceral surface of the left
hepatic lobe to the left of the fossa for the ductus venosus.

The Lesser Omentum encloses the Portal Triad (PV, proper HA, BD) and passes from the
liver to the less curvature of the stomach, and to the first 2 cm of the Superior part of the
duodenum. Composed of:
1. Hepatoduodenal Ligament: encloses structures that passes through the Porta hepatica
as a tent shaped covering and reaches the 1st 2cm of the superior part of duodenum
2. Hepatogastric ligament: between the fissure for ligamentum Venosum of liver and the
lesser curvature of stomach. (Contains the right & gastric arteries anastomosing on the
lesser curvature + coronary vein of stomach)

The visceral surface has impressions made by the nearby structures contacting the liver:
* Duodenal impression: Sup. Part of Duodenum, near gallbladder
* Gastric impression: by the stomach, on the left lobe
* Gallbladder impression: fossa at the Right Anterior groove, by the gallbladder
* Colic impression: by the Right colic flexure & transverse colon at anterior aspect of the
right lobe
* Renal & adrenal impressions: by the Right kidney and suprarenal gland (Right side to
IVC)

In lying position, fluid will accumulate at 2 recesses in the body:

- In the abdomen: Hepatorenal recess (Morisson's pouch)
- In the pelvis: Rectovesical recess (in males) or Rectouterine pouch of
Douglas (in females)

Anatomical lobes:

Anatomically: 2 topographic lobes + 2 accessory lobes by the peritoneal reflections, the fissures
between them and the vessels supplying the liver and the Gallbladder

- On midline plane: attachment of the falciform ligament + L. saggital fissure separates

the large right lobe from the left lobe.

- On visceral surface: R. /L. saggital fissures + Porta hepatica forms the morphologic 2
accessory lobes (which are parts of the anatomic right lobe):
- Quadrate lobe: Anterior and inferior.
- Caudate lobe: posterior and superior. It has the caudate process, which is a
narrow band of hepatic tissue connecting the caudate and right lobes of the liver
posterior to the Porta hepatis. On the left inferior angle of the caudate lobe,
opposite to the caudate process there is the papillary process of caudate lobe)

Functional Sub-division of the liver:

Functionally independent right and left livers (parts or portal lobes), each receives its own branch
of the Proper hepatic Artery and drains its own Hepatic Duct.
Caudate lobe may be considered as a 3rd liver.
The liver may be divided into 4 divisions and 8 surgically resectable segments:
I – Post. Caudate segment
II – Left Post. Lateral Segment

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III – Left Anterior lateral segment

IV – Left Medial segment
V – Right Anterior Medial segment
VI – Right Anterior Lateral segment
VII – Right Posterior Lateral segment
VIII – Right Posterior Medial segment

Blood supply to liver:

Like the lungs, the liver has dual blood supply (afferent vessels). A dominant venous source, and
a lesser arterial one.

- Portal Vein: 70-80% of blood to liver (40% more O2 than IVC)

- Proper hepatic Artery: 20-25% of blood to liver.

The Portal vein is formed behind the neck of pancreas by joining of the superior (and sometimes
inferior) mesenteric vein and the splenic vein. It ascends anteriorly to the IVC as part of the
portal triad, in a posterior position.

The Proper hepatic artery a branch of the celiac trunk (from the common hepatic artery) lies
medially and anteriorly in the portal triad.

At the Porta hepatica, the proper HA and PV terminate by dividing into R., L. and
middle branches, Primary branches which supply the right and left livers. (Also the
caudate lobe) Within each part, secondary branches supply the medial and lateral
divisions of the right and left livers.
Tertiary divisions further supply 7 out of the 8 segments.

The liver is drained by collecting veins, which drain onto the central veins inside the
liver parenchyma.
The central veins unite to form the sublobar veins which drain into the left, right and
middle hepatic veins, which drain into the IVC just under the diaphragm.

Lymphatics of liver:

In the Sub-peritoneal fibrous capsule of Glisson: superficial lymphatics

In the connective tissue of parenchyma: deep lymphatics
Most of the lymph is formed inside Disse's space (peri-sinusoidal space) and drains into
the interlobular portal triad, within the periportal Space of Mall, a tissue space between
the limiting lamina and the portal canal in the liver.

Hepatic lymph nodes celiac lymph Chyle cistern thoracic duct

Innervation:

Hepatic plexus – largest derivative of the celiac plexus.

- Sympathetic from the celiac plexus
- Parasympathetic from the Vagus nerve.

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Biliary ducts and Gallbladder

Hepatocytes Bile Bile canaliculi Herring's ducts Interlobular Biliary ducts
collecting Bile Ducts of interhepatic portal triads R. and L. hepatic ducts (also intermediate)
Common Hepatic duct (joins cystic ducts) Common Bile Duct (part of portal triad)

Common Bile duct:

5-15 cm, formed by union of the cystic and common hepatic ducts
Descends behind the superior part of duodenum, and has a groove on the posterior
surface of the pancreas. Joins the pancreatic main duct of Wirsung and together form the
Hepatopancreatic Ampulla (protrudes in the 2nd descending part of duodenum as Vater's
papilla) guarded by the sphincter of Oddi

** Sphincter of Bayden: around the common bile duct. When it contracts, bile backs up
into the cystic duct for storage and concentration in the gallbladder.

- Arterial supply:
- Cystic artery: from the right branch of proper hepatic artery, proximal part.
- Right hepatic artery: middle part.
- Posterior superior Pancreaticoduodenal artery + Gastroduodenal artery:
retroduodenal part.
- Venous drainage:
- Posterior superior Pancreaticoduodenal vein: distal part.
- Other parts directly from liver!

Gallbladder:

A 7-10 cm, pear-shaped organ that serves as a storage reservoir for bile (~50mL volume)
Lies in fossa for gallbladder on the visceral surface of the liver, at the junction of the left
and right livers
It can be palpable at the junction of the right 9th Intercostal space & the midclavicular
line near the lateral border of the Rectus Abdominis.
Has 3 parts:
o Fundus: wide end, projects from the inf. Surface of the liver. Located at the tip of
the 9th costal cartilage.
o Body: contacts the visceral surface of the liver, transverse colon and 1st part of
duodenum.
o Neck: narrow, directed towards the Porta hepatica makes S shaped bend and joins
the cystic duct.

- Neck and cystic duct are directly above the duodenum.

- Fundus is completely surrounded by peritoneum that binds it to the liver.
Hepatic surface of the gall bladder attaches to the liver by the connective tissue of
the liver's fibrous capsule.

- Cystic duct: (around 4cm) connects the neck of gallbladder to the common hepatic duct.
The mucosa of the neck has Spiral folds (Spiral valves – Heister's valves)
- Helps keep cystic duct open
- Offers additional resistance to sudden dumping of bile (e.g. coughing)

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- Cystic artery: supplies the gallbladder and cystic duct, arises form the right branch of
the proper hepatic artery in the angle between the common hepatic and cystic ducts.
Variation may occur.
- Cystic veins: drain the neck and cystic duct to the PV.
The fundus and body drain directly to the hepatic sinusoids.

- Lymphatics: Hepatic lymph nodes cystic lymph nodes

- Innervation:
- Sympathetic: Celiac nerve plexus
- Parasympathetic: Vagus, also right Phrenic nerve (somatic) – contraction of the
GB and relaxation of the sphincters, though it is usually done by Cholecystokinin
(CCK)

**At diseased states, a dilation/ pouch appears at the junction of the neck of GB and the
cystic duct – Infundibulum of GB (Hartmann's pouch)

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Portal system of veins, Communication between portal and systemic veins

(Porto-caval or porto-systemic anastomosis)
Main vein of portal system: hepatic portal vein.
Blood from GI tract, gallbladder, pancreas, spleen go through portal vein to liver. Terminal branch
in liver: sinusoids drain into hepatic veins inferior vena cava.

Hepatic portal vein formed behind the neck of pancreas from:

- Splenic vein
- Inferior mesenteric vein (usually join to splenic vein)
- Superior mesenteric vein

It then ascend to the liver posteriorly to bile duct and proper hepatic artery in the Porta hepatis and
branches into right and left branches that terminate at the sinusoids.
The blood carried by the hepatic portal .v contains the products of digestion (carbohydrates, fats,
proteins, product of RBC destruction from spleen etc').

Communication between portal and systemic veins: porto-caval anastomosis:

In which portal venous system anastomose with systemic venous system (IVC).
When portal circulation through liver is diminished/ obstructed due to liver disease (e.g.
Cirrhosis) or physical pressure from tumor, blood from the alimentary tract can still reach the
heart via IVC or SVC via these collateral routes.
These routes are available, because of an important fact regarding the Portal vein as a vein: It has
no valves in the lumen! So a retrograde flow of blood inside it is possible!

Main portal-systemic anastomosis:

1) Gastro-esophageal region:

- Between the Submucosa of Inferior esophagus, at the cardia, where Esophageal veins are
drained into SVC (or azygos) (systemic side) and between
- Left Gastric (coronary vein of stomach) (Portal side)

** In the lumen of the esophagus, Varicosities (enlargement) of the Esophageal veins can be
seen, but the esophageal veins are thin and small and can easily rupture due to the high
pressure stop the bleeding by inflating balloon in esophagus.

2) Paraumbilical region:

- Around umbilicus, between Paraumbilical veins (portal side) and

- Subcutaneous veins in the anterior abdominal wall (superficial epigastric .v and lateral
thoracic v.)

** Dilation of epigastric veins around the umbilicus Medusa Head (caput)

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3) Anorectal region:

- Submucosa of Anal canal, between Superior Rectal veins that drain into the IMV (Portal
side) and the
- Middle & Inferior Rectal veins which drain into Internal Iliac veins (systemic side), which
drain into the IVC

** Bleeding in rectum can be seen in the pathological case

4) Retroperitoneal region:

Porto-caval anastomosis formed from veins in the walls of retroperitoneal viscera, such as the
ascending and descending colon, or in bare areas of secondary retro-peritoneal viscera or liver,
around kidney and pancreas passing to the tributaries of the inferior vena cava in the posterior
body wall instead of those of the portal vein

E.g. pancreatic veins PV (portal side) and the renal veins IVC (systemic side)
OR
Colic veins, splenic veins, PV itself (portal side) and the retroperitoneal veins
(systematic) IVC

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The Pancreas:
An elongated accessory digestive gland that lays retroperitonealy, Posterior to the stomach,
between the duodenum loop to the right and spleen to the left, 2 basic functions in:
1. Exocrine secretion: pancreatic juice (Digestion)
2. Endocrine secretion: Insulin/Glucagon/ Somatostatin (Regulation of blood sugar)

Has 4 parts:
1. Head: expanded part held in the C-shaped curve of duodenum to the right of the
Superior Mesenteric Art. /V. Has an Uncinate process that projects from the inferior part
of the pancreatic head. Rests posteriorly on the IVC, right renal artery lumen and left
renal vein, the Common Bile duct is on the posterior superior surface or embedded
inside.

2. Neck: (1-2cm) overlies the superior mesenteric Art. /V., which form a groove on its
posterior aspect next to the stomach pylorus. Behind it the superior mesenteric vein joins
the splenic vein to form the portal vein.

3. Body: continues from neck, moves horizontally, and passes over L2 vertebra, posterior
to omental bursa. Posteriorly it's in contact with aorta, SMA, Left suprarenal gland, left
kidney and renal vessels.

** Between the body (neck) and head there is a notch – Pancreatic notch (under
it goes the SMA, SMV above the uncinate process) and an angle between them
which forms an elevation – the Omental tuber, which is a well marked
prominence that can be seen bulging behind the lesser omentum

4. Tail: lies anteriorly to left kidney, closely related to the splenic hilum and left colic
flexure. Relatively mobile and inside the Splenorenal ligament with splenic vessels (~ L-
1)

Ducts:

- Main pancreatic duct of Wirsung: begins at the tail and goes all along the pancreas,
through parenchyma until the head. Most of the time it joins the common bile duct to
form the Hepatopancreatic Ampulla of Vater's which opens into the major duodenal
papilla of Vater, controlled by Oddi's sphincter (smooth muscle).
- Accessory pancreatic duct of Santorini: opens into duodenum at a higher position (2cm)
above the greater papilla, begins at head and opens into Santorini's papilla (minor
duodenal papilla)

Blood supply: very dense and rich arterial supply, making the pancreatic surgeries one of the
most difficult ones also due to the deep retroperitoneal position of the pancreas.

1. Superior Pancreaticoduodenal artery (anterior/posterior) (branch of the

Gastroduodenal artery): superior part of the head of pancreas
2. Inferior Pancreaticoduodenal (anterior/posterior) (branch of SMA): Inferior part of
the head of pancreas.

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** The Superior & Inferior Pancreaticoduodenal arteries form the 1st Riolan anastomosis
around the head of pancreas.
The importance of those arteries surgically, is that tumors of the head of pancreas require
total surgical removal together with their arterial supply & the duodenum as well, due to
the common arterial supply. This process is known as pancreatoduodenectomy or
Whipple's operation

3. Dorsal pancreatic artery (branch of the Splenic Art.): to the head and body of pancreas
4. Pancreatic branches (from Splenic Art.): Around 10 branches for body and tail
5. Great pancreatic artery (from Splenic Art.): for the body and tail
6. Artery of tail of pancreas (branch of distal part of Splenic Art.): for the tail

Venous drainage:
1. Pancreatic veins: to splenic veins
2. Pancreaticoduodenal vein: to SMV
(Both drain to PV)

Lymphatic drainage:
Pancreatico-splenic lymph nodes – to SMLN

Innervation:
o Sympathetic: abdominopelvic splanchnic nerves
o Parasympathetic: Vagus
Both to the superior mesenteric plexus

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The Spleen
An ovoid, purplish, pulpy mass, delicate and most vulnerable internal organ, located in left upper
abdominal quadrant or Hypochondrium between the 9th and 11th rib in the midaxillary line, with
its longitudinal axis parallel to 10th rib
**Clinically, any fracture of the ribs 9, 10 & 11, due to trauma (Boxing, ski, car accident
etc.) will require an immediate investigation of the spleen for suspicion of rupture and fatal
hemorrhage, due to its position and delicate structure

It is the largest lymphatic organ, participates in the immune defense, hematopoietic functions and
filtering blood but still, its not a vital organ for living.
Usually it is 12 cm long, 7 cm wide, weights about 150 gram

It has a delicate fibro-elastic capsule, (containing collage, elastic fibers & smooth muscle)
surrounded entirely by peritoneum (Intraperitoneal organ) except at the splenic hilum. It Rests
on Left colic (Splenic) flexure, related to 9th -11th ribs and separated from them by the
Diaphragm and Costodiaphragmatic recess.

Relations of the Spleen:

- Anteriorly Stomach
- Posteriorly Left part of diaphragm separates it from the pleura, lung and ribs (9th-11th)
- Inferiorly Left colic flexure (produces the colic impression on spleen).
- Superiomedialy Left kidney (produces the renal impression)

Surfaces of the Spleen:

- Diaphragmatic surface: convex, related to the diaphragm upward.
- Visceral surface, concave facing downward, has 3 parts:
o Anterio-Superior Gastric surface (related to the Stomach)
o Postero-Superior Renal surface (related to the L. Kidney)
o Inferior Colic surface (related to the left colic flexure)

The 3 visceral surfaces meet each other at a sharp margin forming the Hilum of Spleen,
which is the point of entry & exit of vessels & nerves at the Hilar groove.

Ligaments of the Spleen:

- Gastrosplenic ligament : to the greater curvature of stomach, contains:

o Left Gastroepiploic vessels (proximal parts)
o Short gastric vessels
- Splenorenal (Lienorenal) ligament: to left kidney and the posterior wall of trunk. The
Splenic recess of the omental bursa extends to this ligament. It contains:
o Splenic artery /vein
o Tail of pancreas
- Phrenico-splenic ligament: developing from posterior mesogastrium (Phrenicogastric
ligament), attaching the spleen to the diaphragm. it is a portion of the greater omentum,
extending also to the posterior wall as the phrenico-pancreatic ligament
- Phrenicocolic ligament: very important supportive ligament holding the spleen as the
Sustentaculum Lienis and forming the most important component of the Splenic Nest
(Nidus Linealis) on the which the spleen rests. It arises from the diaphragm and reaches
the splenic flexure, prevents spleen from descending and holds it firmly in position.

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** Splenic nest (Nidus linealis): the space / fossa in which the spleen is laying and held
firmly in its position by the nearby splenic ligaments and organs (L. kidney, stomach, L.
colic flexure). The most important component keeping the spleen fixed in position is the
Phrenicocolic ligament, which supports the spleen from below as a shelf, known as the
Sustentaculum lienis

Arterial supply of the Spleen:

- Splenic artery (branch of celiac trunk, largest). Has a tortuous course posterior to
omental bursa, anterior to left kidney and runs at the superior border of pancreas.
At hilum divides to 5-6 branches, but since no anastomosis between them 3 vascular
segments +2 avascular ones.

Veins of the Spleen:

- Splenic vein, formed by:
o Short gastric vein
o Pancreatic veins
o Left Gastroepiploic vein

It joins the Inferior Mesenteric vein behind body of pancreas and at the Neck they
both join the Superior Mesenteric vein to form the Portal vein.

Lymphatic drainage: Pancreatico-splenic and celiac lymph nodes

Nerves: Celiac nerve plexus

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The Respiratory Tract

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Airways
- Conducting Portions (Airways): External nose, Nasal cavity, Nasopharynx, Oropharynx,
Laryngopharynx, larynx, trachea, bronchi, bronchioles (terminal bronchiole, no cartilage)
- Respiratory Portions: Respiratory bronchioles, Alveolar ducts, Atria, Alveolar sacs

The Nose
That portion of the respiratory pathway above the hard palate; includes both the external nose
and the nasal cavity

External nose:
That part of the nose that protrudes from the face and made up of an osseocartilaginous
framework consists of:
- Root: the upper least protruding portion of the external nose situated between the two
orbits made of,
o 2 nasal bones
o 2 frontal processes of maxilla (framing the piriform aperture)
- Dorsum: the external ridge of the nose, looking forward and upward, a continuation of
the 2 nasal bones joined with the triangular cartilaginous plate of the lateral process of
septal nasal cartilage
- Apex (tip): anterior most pointed end of external nose, has a groove formed in the middle
between the 2 major Alar cartilages
- Ala of nose: supporting framework, formed on each side by,
o Large curved major alar cartilages, surrounding the nostrils with the lateral and
medial cruses
o 3 or 4 small minor alar cartilages (sesamoid)
o Fibroareolar or fibro-fatty tissue

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The nostrils (nares) are elliptical, forming the entrance to the right and left nasal cavity, in front
which lies the Nasal vestibule (the anterior part of the nasal cavity, especially that enclosed by
cartilage)
The lumen of the nasal vestibule is lined with skin and short brush-like hairs (Vibrissae) of
vestibule of nose. The skin over the external nose is rich with sebaceous glands.

Around the nose there are many subcutaneous mimetic muscles, whose fibers mainly insert on
the skin of the ala of nose and Nasolabial groove (a furrow between the wing of the nose and the
lip), these muscles also contribute to the dilation and constriction of the nostrils, and they are:
- Procerus: from membrane covering bridge of nose, assists the Frontalis
- Nasalis:
o Transverse part: forming an aponeurosis across the bridge of the nose; compresses
the nostrils
o alar part: attaching to the wing of the nose; dilates the nostril
- Levator labii superioris alaeque nasii: elevates upper lip and wing of nose

Arterial supply of the external nose:

- Angular artery: the terminal branch of the facial artery, for muscles and skin of side of
nose by lateral nasal branches
- Dorsal nasal artery: terminal branch of the ophthalmic artery, for the skin of side of root
of nose
- External nasal branches: terminal branch of anterior ethmoidal artery, runs on the
dorsum of nose
- Infraorbital artery: branch of 3rd part of maxillary artery, for the upper lip and tip of the
nose

Venous drainage of the external nose:

- Facial vein
- Superior ophthalmic vein
o There is an anastomosis between these 2 veins, between the medial angle of eye
and root of the nose. So in inflammation involving the lateral part of face and
external nose, bacteria can reach the deep venous sinuses of the cranial cavity
causing venous sinus thrombosis and meningitis

Innervation of the external nose:

- Ophthalmic nerve, sensory via Nasociliary (anterior ethmoidal External nasal
branches) and Infra and supratrochlear branches (Root and dorsum)
- Maxillary nerve, sensory via infraorbital branch (wings of nose)
- Facial nerve, motor, for mimetic muscles

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Nasal Cavity:
The cavity divided by the nasal septum into right and left halves, lined with ciliated respiratory
mucosa, extending from the external nostrils anterioinferioly to the choana posteriorly to
continue as the nasopharynx. Communicates with the paranasal sinuses through their orifices in
the lateral wall
Each half of the nasal cavity has 4 walls:

A. Superior wall: the roof of nasal cavity, made by:

- Nasal bone, most anterior portion
- Nasal part of frontal bone
- Cirbriform plate of ethmoid bone, central superior part, a horizontal lamina from which
are suspended the labyrinth, on both sides, and the perpendicular plate in the center; it fits
into the ethmoidal notch of the frontal bone and supports the olfactory lobes of the
cerebrum, being pierced with numerous openings for the passage of the olfactory nerves.
- Body of sphenoid bone, most posterior part

B. Inferior wall: the floor of nasal cavity is the hard palate (See palate section in the digestive
tract), made by:

- Palatine process of maxilla anteriorly, containing:

o Median and transverse palatine suture
o Nasal crest, on which the vomer inserts
o Incisive canal and foramen, a Y-shaped passage which connects the two halves of
the nasal cavity with the bony palate.

- Horizontal plate of palatine bone, containing:

o Greater palatine foramen and canal
o Lesser palatine foramina and canals
o Posterior nasal spine
o Median and transverse palatine suture

- The Premaxilla or incisive bone:

o the anterior and inner portion of the maxilla, which in the fetus and sometimes in
the adult is a separate bone; the incisive suture runs from the incisive canal
between the lateral incisor and the canine tooth

C. Lateral wall: bony wall, formed by

o Maxilla anteriorly (frontal process)
o Lacrimal bone
o Parts of Ehtmoid bone:
- Superior Nasal Concha (+ ethmoid air cells)
- Middal Nasal Concha
o Inferior Nasal Concha (separate bone)
o Perpindicular process of Palatine bone posteriorly (+ orbital & sphenoidal
processes)

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Each concha projects over a nasal meatus of the same name, into which paranasal sinsuses
and nasolacrimal durcts open:

- Superior nasal meatus: under the small, superior nasal concha, into which the Posterior
ethmoidal air cells open

** Sphenoethmoidal recess: a small cleft like pocket of the nasal cavity situated
between the superior concha, nasal septum and body of sphenoid bone into which
the sphenoid sinuses drain
Immediately below the sphenoethmoidal recess, there is the Sphenopalatine
foramen bordered by the body of sphenoid bone superiorly and the
sphenopalatine notch inferiorly (composed of 2 processes: Orbital and
Sphenoidal)

- Middle Nasal meatus: below the large middle nasal concha, into which the frontal,
maxillary and Anterior Ethmoidal air cells open
The inferior portion of the ethmoid bone forms the uncinate process, which projects into
the middle nasal meatus and covers the orifice of the maxillary sinus. The middle
Ethmoidal air cells form the Ethmoidal bulla that bulges over the uncinate process
Between the Ethmoidal bulla and uncinate process we can find the semilunar hiatus
The middle nasal meatus has an anterior expanded portion, just above the nasal vestibule
called: the atrium of middle nasal meatus.

There is a groove leading from atrium of middle nasal meatus to the olfactory area of
nasal cavity called the olfactory sulcus of nasal cavity

** Agger nasii (nasal ridge or Nasoturbinal concha): is an elevation on the lateral wall of the
nasal cavity lying between the atrium of the middle meatus and the olfactory sulcus; it is formed
by the mucous membrane covering the base of the ethmoidal crest of the maxilla (a ridge on the
upper part of the nasal surface of the frontal process of the maxilla that gives attachment to the
anterior portion of the middle nasal concha)

- Inferior nasal meatus: under the inferior nasal concha, into which the nasolacrimal duct
open

** The 3 nasal meatus open medially into the Common nasal meatus (space between the
conchae and nasal septum)

The nasal mucosa in the lateral wall has 3 parts:

1) Nasal vestibule: anteriorly, forming the entrance to the nasal cavity proper. Lies
within the nostrils and lined with skin (stratified squamous keratinized epithelium)
2) Respiratory region: reflects the bony relief pattern of the lateral nasal wall, the
mucosa is covered by pseudostratified ciliated columnar epithelium (respiratory
epithelium) and contains many nasal glands

** The border between the nasal vestibule and respiratory region is a curved
ridge called: Limen Nasi

3) Olfactory region: circumscribed area on the lateral nasal wall above the superior
nasal concha (upper 1/3)

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Arterial supply of the lateral wall of nasal cavity:

- Anterior Ethmoidal artery: branch of ophthalmic artery, supplies the anterior
Ethmoidal air cells, anterior upper part of nasal mucous membrane, and skin of
dorsum of nose.
- Posterior Ethmoidal artery: branch of ophthalmic artery, supplies the posterior
ethmoidal cells and upper posterior part of lateral wall of nasal cavity.
- Sphenopalatine artery: branch of 3rd part of maxillary artery, supplies and inferior
posterior portion of lateral nasal wall and septum (lateral posterior superior branches)
- Lateral nasal branches of facial artery: supply the vestibule of nose
- Alar branches of superior labial artery
- Perforating branches of Greater palatine and anterior superior alveolar

Venous drainage of the lateral wall of nasal cavity, has same course and name as arteries,
drain into:
- Ophthalmic vein via Ethmoidal foramina
- Pterygoid venous plexus via sphenopalatine foramen
- Facial vein via nasal vestibule

Innervation of the lateral wall of nasal cavity:

1) Ophthalmic nerve: anterior and superior portion
o Anterior Ethmoidal nerve (giving the internal nasal branches)
o Posterior Ethmoidal nerve
2) Maxillary nerve: Inferior and posterior portion
o Posterior Superior lateral nasal branches: branches of pterygopalatine
ganglion to upper posterior part of lateral wall of nasal cavity, including
superior and middle nasal concha/meatuses, and posterior Ethmoidal sinuses.
o Posterior inferior nasal branches: branches of greater palatine nerve to
posterior inferior lateral wall of nasal cavity, including posterior aspect of
mucosa over posterior portion of inferior nasal concha and meatus
o Infraorbital nerve: gives the internal nasal branches for the most anterior and
inferior portion of the nasal septum and lateral wall
o Anterior superior alveolar branches: of infraorbital nerve, supply the anterior
inferior portion of the lateral wall

D. Medial wall: the nasal septum, the wall dividing the nasal cavity into halves; it is composed
of a central supporting skeleton covered on each side by a mucous membrane. Composed of
2 parts:

- Bony part: its posterior and inferior portion, sub composed of:
o Perpendicular plate of ethmoid bone, inserting on the roof of nasal cavity
sagittaly, forming the upper part of the bony septum
o Vomer, trapezoidal shaped bone articulating with the anteroinferior part of the
perpendicular plate of ethmoid, and body of sphenoid bone and inserting caudally
on the nasal crest of the nasal cavity formed by the maxillae, and two palatine
bones
The free posterior margin of the vomer forms the medial boundary of the Choana
o Nasal crest of maxilla + (anterior nasal spine)
o Nasal crest of palatine bone + (posterior nasal spine)

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- Cartilaginous parts: a thin cartilaginous plate located between vomer, perpendicular

plate of the ethmoid, and nasal bones, and completing the nasal septum anteriorly. It has a
long posterior process that is inserted in the gap between the 2 thing bony plates (vomer
and perpendicular plate of ethmoid).
At the dorsum of nose, the cartilaginous septum contributes to the formation of the
external nose with a T-shaped lateral process, and joined inferiorly by the medial crus of
the Major alar cartilage
Vomeronasal cartilage: a narrow strip of cartilage located between the lower edge of the
cartilage of the nasal septum and the vomer.

** Vomeronasal organ of
Jacobson: a fine vestigal
horizontal canal, ending in a
blind pouch, in the mucous
membrane of the nasal septum,
beginning just behind and
above the incisive duct; a
structure that usually regresses
after the 6th month of
gestation. In many lower
animals, it functions as an
accessory olfactory organ.

The mucosa of the nasal septum:

1) Respiratory region: the mucosa is
covered by pseudostratified ciliated columnar epithelium (respiratory epithelium) and
contains many nasal glands
2) Olfactory region: in the upper part of the nasal septum where it meets the Cribriform
plate

Arterial supply of the nasal septum:

- Anterior Ethmoidal artery: branch of ophthalmic artery, supplies the anterior Ethmoidal
air cells, anterior upper part of nasal mucous membrane, and skin of dorsum of nose.
- Posterior Ethmoidal artery: branch of ophthalmic artery, supplies the posterior ethmoidal
cells and upper posterior part of lateral wall of nasal cavity.
- Sphenopalatine artery: branch of 3rd part of maxillary artery, supplies and inferior
posterior portion of lateral nasal wall and septum. Travels on the septum until reaching
the incisive canal, where it anastomosis with the ascending branch of greater palatine
artery
- Superior Labial artery: branch of facial, gives the nasal septal branch for the
anteroinferior aspect of the septum

** Kiesselbach (Little's) area: a well developed cavernous area on the anterior portion of
the nasal septum rich in capillaries (Kiesselbach plexus) and often the site of epistaxis

Venous drainage of the nasal septum, has same course and name as arteries, drain into:
- Ophthalmic vein via Ethmoidal foramina
- Pterygoid venous plexus via sphenopalatine foramen
- Facial vein via nasal vestibule

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Innervation of the nasal septum:

1) Ophthalmic nerve: anterior and superior portion
o Anterior Ethmoidal nerve (giving the internal nasal and septal branches)
o Posterior Ethmoidal nerve
2) Maxillary nerve: Inferior and posterior portion
o Nasopalatine nerve of Scarpa: a branch from the pterygopalatine ganglion,
passing through the sphenopalatine foramen, crossing to and then down the nasal
septum, reaching through the incisive foramen to anastomose with the greater
palatine nerve and supply the nasal septum and mucosa of the hard palate
o Posterior Superior medial nasal branches: branches of maxillary nerve or
nasopalatine nerve to upper posterior part of lateral wall of nasal cavity,
including superior and middle nasal concha/meatuses, and posterior Ethmoidal
sinuses
o Infraorbital nerve: Give the internal nasal branches for the most anterior and
lower part of septum and lateral wall

3) Olfactory nerves: concerned with smell, arising from cells in the olfactory epithelium in
the superior part of the lateral and septal walls of the nasal cavity. The central processes
of these cells (forming the olfactory nerve CN-I) pass through the numerous holes in the
cirbriform plate and end the olfactory bulb, the rostral expansion of the olfactory tract

Lymphatic drainage of the nose:

- Anterior part of nose: drains into the Submandibular and Superficial lymph nodes of the
anterior neck
- Posterior part of nose: drains into the retropharyngeal and deep cervical lymph nodes

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Paranasal sinuses
These sinuses are air filled extensions of the respiratory part of the nasal cavity. They are named
according to the bones in which they are located and lined by mucous membrane continuous
with that of the nasal cavity, there are 4 sinuses:

1. Frontal sinus:
Located between the outer and inner tables of the frontal bone, posterior to the supercillary
arches, the sinuses can be seen by the age of 7. The right and left sinuses are rarely equal in
size in the same person, and the septum between them usually is not found in the median
plane.
The sinus often has 2 parts:
- Vertical: found in the squamous part of the frontal bone
- Horizontal: found in the orbital part of the frontal bone

When the supraorbital part is large, its roof forms the floor of the anterior cranial fossa and
it's floor form the roof of the orbit.

The frontal sinuses vary in size from as small as 5 millimeters to large spaces extending
laterally to the greater wing of the sphenoid bone. The sinus may have separate forntonasal
ducts that drain inferiorly to the infundibulum of the middle nasal meatus, which drains to the
semilunar hiatus.

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2. Ethmoidal sinuses:
These sinuses comprise several small cavities called Ethmoidal cells that are found within the
ethmoidal labyrinth of the lateral mass of the ethmoid bone. The cells form the ethmoid
labyrinth which is located between the nasal cavity and the orbit. The number of cells varies
between 3-18. The cells are larger when the number is small. Medially they are separated by
the orbit by a thin paper plate of the ethmoid bone, Lamina Papyracea

For purposes of description the cells are divided into anterior, middle and posterior groups.
The middle cells, or "bullar cells", because they form the Ethmoidal bulla, a swelling on the
superior border of the semilunar hiatus.

According to their variable location, the cells can open into the superior nasal meatus
(posterior group) or the middle nasal meatus (anterior group)

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3. Sphenoidal sinuses:
Found in the body of the sphenoid bone. They occupy a variable amount of this bone and
may extend to the wings. The Sphenoidal sinuses are located posterior to the superior part of
the nasal cavity, bordered anteriorly by the ethmoidal air cells. The 2 sinuses are separated
by a bony septum that is usually not found in the median plane. Because of these sinuses the
body of the sphenoid bone is fragile hollow structure. Only thin plates of bone separates the
sinuses from several important structures:
- Optic nerve in the canal (anteriorsuperiorly)
- Optic chiasm (superiorly)
- Hypophysial fossa with pituitary gland (posteriorly)
- Internal carotid arteries in the carotid sulcus and cavernous and intercavernous sinuses
and their contents (laterally)
- Roof of nasopharynx, Pterygoid canal, Palatovaginal canal (inferiorly)

The sphenoid sinus drains into the sphenoethmoidal recess

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4. Maxillary sinuses (Antrum of Highmore):

This is the largest pair of paranasal sinuses. They are pyramidal-shaped cavities that may
occupy the entire bodies of the maxillae. The apex of the sinus may extend as far as the
zygomatic bone; the base forms the inferior part of the lateral wall of the nasal cavity. The
roof is formed by the floor of the orbit, and its narrow floor is formed by the alveolar process
of the maxilla (dental arch). Anterolaterally it's bounded by the Facial surface of maxilla,
and posteriorly by the maxillary tuberosity

The roots of the maxillary teeth, especially the first 2 molars often produce conical elevations
in the floor of the maxillary sinus. The lowest point of the sinuses is between the 1st premolar
tooth and molars.

The maxillary sinus drains into the middle nasal meatus through the hiatus semilunar by an
aperture in the superior part of its base. Because of the location of this opening, it's
impossible for fluid in the sinus to drain when the head is erect until the sinus is nearly full.

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Posterior nasal apertures (Choanae)

Both nasal cavities open into the nasopharynx through posterior nasal aperture each, or the
choana. The margins or borders of the choana are:

- Superior border: formed by the body of sphenoid bone, continuous superolaterally with
the medial plate of the Pterygoid process (penetrated by the Pterygoid canal)
- Medial border: formed by the vomer, which has an Ala inserted superiorly on the roof of
the choana, and inferiorly with the posterior nasal spine of palatine bone
- Inferior border: formed by the horizontal plate of the palatine bone
- Lateral border: perpendicular plate of palatine bone

From a posterior view of the choana, we can visualize the inferior and middle conchae, as well
as the Ethmoidal bulla and Uncinate process

** (The following brief description of pharynx is taken from the pharynx section of the GI tract, more details; you
should read that section above about the pharynx)

The pharynx is the continuation of the GI tract after the oral cavity. It’s a fibromuscular tube
that is used as a pathway for both food and air.
The Pharynx is divided to 3 parts:
- An upper Nasopharynx that receives the posterior openings of the nasal cavity,
the 2 Choana.
- Middle Oropharynx, behind the oral cavity (after the isthmus of fauces)
- A lower Laryngopharynx, behind the Larynx.

In the respiratory tract, the air will usually go from the choana into the nasopharynx into the
Oropharynx and then into the larynx

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The Larynx
The organ of voice production; the part of the respiratory tract between the pharynx and the
trachea; it consists of a framework of cartilages and elastic membranes housing the vocal folds
and the muscles which control the position and tension of these elements.

Cartilages, Skeleton of the larynx:

1. Thyroid cartilage: Hyaline type of cartilage that has 2 lamina, forming anteriorly the
superior thyroid notch (Adam's apple) has an oblique line that divides the lamina into
anterior and posterior facet. Has a superior & inferior horn. The inferior one articulates
with the cricoid cartilage as a Cricothyroid joint (Hinge type, 1 transverse axis). Superior
horn articulates with the hyoid bone.
2. Cricoid cartilage: ring shaped, with the lamina laying posteriorly, on the upper edge of
lamina 2 articular surfaces for Arytenoid cartilage. On the lateral surface articular surface
for the inferior horn of thyroid cartilage. Hyaline type of cartilage.
3. Arytenoid cartilage: sits on the upper lamina of cricoid cartilage, and articulates with the
cricoid cartilage vial the Cricoarytenoid joint (Pivot type with 1 vertical axis). It is an
Elastic type of cartilage. Has 3 process:
- Anterior process (vocal process): from this process arise the vocal cords
- Lateral process (muscular process): Where Posterior and lateral cricoarytenoid
muscles are inserted.
- Posterior process: Is the apex of the pyramidal shaped cartilage. It carries the
corniculate cartilage (of Santorini).
4. Epiglottis cartilage: lies against the internal surface of thyroid cartilage, elastic type of
cartilage. Has the Stem (petiolus) that forms the Epiglottic tubercle on the mucosa and an
oval lamina which is concave posteriorly and perforated by the glands.

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Ligaments of the larynx:

A) Extrinsic (Outer) ligaments: fix the larynx between the hyoid bone and trachea.

1. Thyrohyoid membrane: attached from the superior border and the superior horns of
the thyroid cartilage to the posterior surface of the body and greater horn of the hyoid
bone. The outer surface of this membrane is covered by the Infrahyoid muscles. The
middle part of the membrane is thicker and forms the median thyrohyoid ligament,
which is pierced on each side by the superior laryngeal artery and vein and the internal
laryngeal nerve. The tips of the superior horns of the thyroid cartilage are connected to
the greater horns of the hyoid bone by the lateral thyrohyoid ligaments, which are also
thickenings of the thyrohyoid membrane. A small cartilage named triticeal cartilage lies
in this ligament.

2. Thyroepiglottic ligament: Attaches the anterior lower part of the epiglottis to the
thyroid cartilage.
3. Hyoepiglottic ligament: Attaches the anterior upper part of the epiglottis to the hyoid
bone.
4. Cricotracheal ligament: The inferior border of the cricoid cartilage is joined to the
first ring of the trachea by this ligament

B) Intrinsic (Inner) Ligaments: fibroelastic membranes that joins the different parts of laryngeal
skeleton.

1. Quadrangular membrane: It extends from the lateral margins of the epiglottis within
the aryepiglottic fold and attaches to the Arytenoid and corniculate cartilages. The
inferior free edge is thickened to form the vestibular ligament (false vocal cord). The
superior edge is also free and it is covered with aryepiglottic fold of mucosa. The
anterior fixed border is the lateral edge of epiglottis, and the posterior fixed border is the
Arytenoid cartilages

2. Triangular membrane: This membrane arises from the inner surface of the cricoid
arch and it consists of:
- The anterior or superficial part or border, also called the median Cricothyroid
ligament (Conicate ligament), extends from the upper border of the anterior part
of cricoid cartilage to the lower border of the thyroid cartilage
- The lateral part of this membrane extends from the superior inner border of the
cricoid cartilage to the inner surface of the thyroid angle and posteriorly to the tip
of the vocal process of the Arytenoid cartilage.
- The superior edge is free and thickened between its two attachments, the angle
of the thyroid lamina and vocal process of the Arytenoid cartilage, and forms the
vocal ligament (true vocal cord).

The 2 triangular membranes on both sides form together the Conus elasticus
(cricovocal membrane), or the Cricothyroid membrane (extending between the arch of
the cricoid cartilage and the inferior edge of the thyroid lamina on each side of the
midline, which is occupied by the thicker median Cricothyroid ligament)
The Conus elasticus and the 2 vocal cords form the elastic wall of the tone producing
mechanism, Lip Pipe

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Muscles of the Larynx:

1. Cricothyroideus: originates from the anterior surface of the arch of the cricoid, inserted either
on the wing of the thyroid on inferior horn of the thyroid.
Nerve supply: superior laryngeal nerve (the only laryngeal muscle innervated by it).
Action: tense the vocal folds by tilting the thyroid cartilage via the Cricothyroid joint.
Controls the rough tension of the voice

2. Lateral cricoarytenoid: originates from the upper margin of the arch of the cricoid cartilage,
inserted to the muscular process of the Arytenoid cartilage.
Nerve supply: recurrent laryngeal nerve.
Action: narrows the Rima glottides

3. Posterior cricoarytenoid: originates from both sides of the posterior surface of cricoid,
inserted on the muscular process of the Arytenoid.
Nerve supply: recurrent laryngeal nerve.
Action: widens the Rima glottides. It is the antagonist for lateral cricoarytenoid, and the
only muscle that opens (widens the Rima glottides)

4. Vocalis: originates from posterior surface of thyroid cartilage, runs within the vocal fold and
inserted into the vocal process of the Arytenoid.
Nerve supply: recurrent laryngeal nerve.
Action: shortens and relaxes the vocal cords. (Control the soft tension of voice).

5. Thyroarytenoid: originates from the inner surface of the thyroid cartilage (together with
Vocalis muscles). Inserted into the muscular process and the outer surface of the Arytenoid
Nerve supply: recurrent laryngeal nerve.
Action: constrict the Rima glottides.

6. Thyroepiglottic: originates from the inner surface of the thyroid cartilage (in common with the
Thyroarytenoid muscle), inserted into the epiglottis.
Nerve supply: recurrent laryngeal nerve.
Action: depresses the base of the epiglottis, constricting the entrance into larynx.

7. Oblique and transverse Arytenoid (Inter-Arytenoid): the fibers crossing each other between
the posterior surfaces of the 2 Arytenoid cartilages.
Nerve supply: recurrent laryngeal nerve.
Action: narrows the Rima glottides.

8. Aryepiglottic: A band of fibers of the oblique Arytenoid muscle that extend to the side of the
epiglottis.
Nerve supply: recurrent laryngeal nerve
Action: lowering the epiglottis therefore assists in narrowing the entrance to larynx.

The aryepiglottic fold envelops the corniculate cartilage (of Santorini) and the inconstant
Cuneiform cartilage (of Wrisberg). Both are visible through the mucosa and produces tubercles
with similar names

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Mucous membranes & spaces of larynx:

Most parts of larynx are covered by mucous membranes, mucosal folds that can be seen:
- Aryepiglottic folds: runs from both sides of epiglottis to Arytenoid cartilage.
- Piriform recess: between aryepiglottic folds to thyroid cartilage. It diverts food away
from the entrance to larynx.
- Plica Nervi laryngei (Laryngeal nerve folds): runs across the piriform recess, seen in the
mucosa. Formed by the underlying superior laryngeal vessels and nerve.
- Vestibular folds (ventricular folds), or false vocal cord: formed by some muscle fibrils
and the tip of quadrangular membrane (lower margin).
- True vocal folds or cords: formed by Vocalis muscle and vocal ligament.

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Laryngeal Aditus or inlet: he aperture between the pharynx and larynx, bounded by the
superior edges of the epiglottis (anteriorly), the aryepiglottic folds (laterally), and the
mucosa between the arytenoids (posteriorly)
Vestibule of larynx: the space from laryngeal Aditus until the vestibular folds or rima
vestibuli. Its anterior wall is formed by epiglottis; the lateral wall is the quadrangular
membranes and posteriorly the mucosa over the arytenoids.
Rima vestibuli: the interval between the false vocal cords or vestibular folds
Rima glottides: the interval between the true vocal folds, subdivided into:
o Intermembranous part (glottis vocalis): the portion of the opening anterior to the
vocal processes of the arytenoid cartilages bounded by the vocal ligaments; this
portion is closed by contraction of the lateral cricoarytenoid (muscle) only during
whispering
o Intercartilaginous part (glottis respiratoria): the opening between the vocal
processes of the arytenoid cartilages; this part is open during whispering and is
closed during phonation and the Valsalva maneuver.
Laryngeal ventricle: the space between the vestibular folds to true vocal folds. Has
lateral extension called laryngeal saccule
The space below vocal cords is called infraglottic cavity

Epithelium

Epiglottis: is covered by stratified squamous epithelium on its anterior portion

(continuous with posterior surface of tongue). The posterior surface has a ciliated,
pseudostratified columnar epithelium containing seromucous glands. This epith’
continuous over vestibule of larynx, false vocal cords and ventricle
True vocal cords: covered by stratified squamous non keratinized epith’.

Innervation:

1) Superior laryngeal nerve: (is a direct branch of Vagus) It divides into internal and
external branches. The internal branch pierces the thyrohyoid membrane to supply
innervation to the mucosa above the vocal folds; the external branch travels with the
superior thyroid artery and supplies the Cricothyroid muscle.

2) Inferior laryngeal nerve: (is a terminal branch of recurrent laryngeal) innervates the
mucosa of the larynx below the vocal folds, and the upper trachea, in addition to
providing motor innervation to all of the intrinsic muscles of the larynx except
Cricothyroid.

Blood supply:

The arterial blood supply of the larynx is derived from the laryngeal branches of superior and
inferior thyroid arteries. Most of the arteries anastomose freely with each other.

1) Superior laryngeal artey: It is a branch of the superior thyroid artery, which comes off
of the external carotid artery. It enters the larynx through the thyrohyoid membrane,
along with the internal branch of the superior laryngeal nerve, and supplies the muscles
and mucous membranes in the superior portion of the larynx.

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2) Inferior laryngeal artery: It is a branch of the inferior thyroid artery, which comes off
of the thyrocervical trunk of the subclavian artery. It ascends on the trachea, together with
the recurrent laryngeal nerve, and enters the larynx beneath the lower border of the
inferior constrictor muscle. It supplies the muscles and mucous membranes in the lower
part of the larynx.

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Trachea
Located in superior mediastinum, begins at the larynx at the level of cricoid cartilage
(C6), and bifurcates into 2 main bronchi (Right & Left) at the level of transverse thoracic
plane (or sternal angle, Th4/Th5). The angle of bifurcation is 50º-100º, with an average
of 75º with 35º on the right side (right bronchus is more vertical) and 40º on the left
9-15 cm length, has horse shoes C-shaped supporting cartilage rings (16-20)
Has carina downward/backward projection of last tracheal cartilage forms keel like
ridge separating openings of R/L bronchi
R. Bronchus (primary/main/principle) ~ 2 cm
Shorter, wider, more vertical than L. bronchus. So the tendency for foreign
bodies to go in it.
Runs under arch of azygos vein and divides into 3 lobar bronchi. The R. sup.
Lobar bronchus Epiarterial position (above the right pulmonary artery),
all rest hypoarterial (below the artery)
L. Bronchus (primary/main/principle) ~ 5 cm
Runs Inferolaterally to the arch
of aorta, crosses anteriorly to
esophagus and thoracic aorta,
and divides in 2 lobar bronchi
Also crossed by arch of aorta
superiorly and proximally, and
by left pulmonary artery distally.

Important Note: the bronchitic tree always

divide in the so called Dichotomic pattern of
division, which means every branch divides into 2
only all the time!!! (Not more!!)(Like cells splitting
each into 2)

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The Pleurae (Membrana Succingens)

Each lung is invested and enclosed by a serous pleural sac that consists of 2 continuous
membranes:
Visceral pleura: invests all surfaces pf the lung and gives the shinny smooth appearance

Parietal pleura: lines the different parts of the wall of the pleural cavity; called costal,
diaphragmatic, and mediastinal, according to the parts invested
Pleural cavity: is a potential space between the 2 layers that contains capillary layer of
serous pleural fluid for lubrication of plural surfaces. The tension (Pressure) in this cavity is
more negative than the lung itself, which good for the Inspiration (enables the inflation of the
lung), but in the case of perforation of the thoracic wall, this tension becomes normal and
same as the lung so this leads to the collapse of the lung. Clinically, air in the pleural cavity
is know as Pneumothorax

Visceral Pleura (Pulmonary pleura):

Covers the lungs and adheres to all of its surfaces, including surfaces within fissures.
Provides the lung with a slippery surface, continues with the Parietal pleura at the hilum of
the lung around the root of the lung pulmonary ligament

Parietal Pleura: covers the pulmonary cavities, has 4 parts:

1) Costal part: covers the surfaces of the thoracic wall, separated from the internal
surface of the thoracic wall by the Endothoracic fascia, good for extra-pleural
intrathoracic surgical access
2) Mediastinal part: in the lateral parts of the mediastinum and at the hilum of the lung
it reflects laterally onto structures making up the root of lung (pulmonary sleeve).
Inferior to the root of lung the reflection or continuity between the parietal and
visceral pleura is an empty double layer of pleura, the Pulmonary ligament
(immediately anterior to the esophagus)
3) Diaphragmatic part: covers the thoracic superior surface of the diaphragm, except
along its costal attachments and the fusion with the pericardium. A this elastic layer
of Endothoracic fascia, the Phrenicopleural fascia, connects the diaphragmatic pleura
with the muscular fibers of the diaphragm
** Cervical pleura: (special part) or the Pleural Cupula extends through the superior
thoracic aperture 2-3 cm above the midclavicular line into the root of neck, forming a
cup shaped pleural dome over the apex of lung. It's reinforced by a fibrous extension of
the Endothoracic fascia or the Supra-pleural membrane of Sibson, which attaches to the
inner border of the first rib and to the transverse process of the seventh cervical vertebra.
The whole structure is covered by the Scalenus tent, made by the 3 scalene muscles
Lines of Pleural reflections:

1) Sternal line: sharp, between costal and mediastinal pleura

2) Costal line: sharp/ oblique, between diaphragmatic and costal pleura
3) Vertebral line: rounder reflection, between costal and posterior mediastinal part

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Borders of the Pleura:

We start 2-3 cm above the midclavicular line (Cupula), then we descend in an oblique line into
the 2nd Intercostal space, near the sternum after that we go down parallel to sternum into:
- 6th rib: Sternal line
- 7th rib: Midclavicular line
- 8th rib: Anterior Axillary line
- 9th rib: Midaxillary line
- 10th rib: Posterior Axillary line
- 11th rib: Scapular line
- 12th rib / Spinous process of Th-11: Vertebral line,
- then go up vertically to Th-1

** on the left side, due to the presence of the heart, we descent from the 2nd IC space up to
the 4th rib, and then we go laterally in an arch shaped line and then go to the 6th rib. This
notch created by this arched line is shallower than the normal Cardiac notch of lungs and
allows a part of the pericardium to be in direct contact with the anterior chest wall, which is
very important in Pericariocentesis (Needle or catheter drainage of the pericardium)
Recesses:
Lungs do not occupy the whole pulmonary cavity during expiration, and because of this, you can
find recesses at the junction (or reflection) of the different parts of the parietal pleura. This is
different form the recesses in the pericardium because in that case they are made by both parietal
and visceral layers.
- Costodiaphragmatic (phrenicocostal) recess: between the diaphragm and the costal
layer of the parietal pleura. It is the lowermost point of the Pleural cavity, and fluid is
accumulated in it, which gives the ability to drain it by a needle via the 9th IC space.
During inspiration, the inferior border/ margin of the lung descends to it and fills it
- Phrenicomediastinal recess
- Costomediastinal recess

Blood supply of the parietal pleura:

- Arterial supply: from the arteries that supply the thoracic wall internal thoracic,
intercostals and Musculophrenic arteries.

- Venous drainage: into systemic circulation by adjacent parts of thoracic wall.

Blood supply of visceral pleura:

- Arterial supply: bronchial arteries

- Venous drainage: into (via bronchial veins) pulmonary veins.

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The Lungs
A pair of viscera occupying the pulmonary cavities of the thorax, the organs of respiration in
which aeration of the blood takes place

The root of the lungs is all the structures entering or leaving the lung at the hilum, forming a
pedicle invested with the pleura, it contains:

Bronchi (Major, Principal)

Pulmonary arteries
Pulmonary Veins (superior, inferior)
Pulmonary plexus & Nerves (Parasympathetic, Sympathetic, VSA)
Bronchial Arteries & Veins
Lymphatics
Medial to the hilum, the root is enclosed within the area of continuity between the parietal and
visceral layers of pleura as Pleural Sleeve or mesopneumonium, which continues downward
as The Pulmonary ligament

Each lung has:

Apex: blunt, rounded superior end of lung ascending above the level of 1st rib into the
root of neck that is covered by cervical pleura (cupula)(see the discussion of the pleura)

3 Surfaces:
- Costal: large, smooth, and convex. Related to costal pleura, separated from ribs/
cartilage and intercostal muscles. Posterior part of it is related to vertebrae.
- Mediastinal: concave, includes hilum and root of lungs. It has grooves and
impressions. (See later)
- Diaphragmatic: concave, forms base of lungs rests on dome of diaphragm
Lateral & posterior thin, sharp margin projects into costodiaphragmatic
recess

3 Borders (Margins): where 2 of the surfaces meet, forming a sharp end

- Anterior: between costal and mediastinal surfaces meet anteriorly and overlap
the heart
- Inferior: circumscribes the diaphragmatic surface of lung and separates it from
costal and mediastinal surfaces
- Posterior: where costal and mediastinal surfaces meet posteriorly

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The Right Lung:

Larger and heavier than the left lung, but shorter and wider because of high R. dome of
diaphragm and the inclination of the heart on the left
Has 3 lobes - Upper
Middle Separated by oblique and horizontal fissures
Lower
Oblique fissure: separates the upper and middle lobes from the lower lobe, begins
posteriorly above the head of 4th rib in the paravertebral line and reaches the 6th
sternocostal joint anteriorly after crossing the 5th rib
Both fissures are important in percussing dullness

Horizontal fissure: deep fissure that separates the upper and middle lobes of the right
lung. runs from oblique fissure in the midaxillary line following the 4th rib and cartilage
obliquely (so its not really horizontal)
Has 3 lobar (secondary) bronchi and 10 segmental (tertiary) bronchi (with artery)
Has Impressions for:
Azygos Vein : above hilum (arch like) (sometimes produces the Azygos lobe if
it passes through the tissue of the lung to reach the SVC)
SVC (after root)
Esophagus (behind root)
Cardiac impression (by right atrium)
Costal impressions made by the ribs on the costal surface
Position of structures at the right hilum
Superior & inferior anterior – 2 pulmonary veins
Superior posterior – pulmonary arteries
Posterior – 2 R. Pulmonary bronchi (Bronchus is in Epiarterial position
or at the same level at the hilum)
The Left Lung

Has 2 lobes
upper divided by the
Lower oblique fissure
Oblique fissure follows 6th rib line
Has the Lingula – a tongue shaped inferomedial projection from the anterior aspect of the
upper lobe of the left lung which bounds the cardiac notch inferiorly and corresponds the
middle lobe of the right lung
Has impressions
Cardiac impression by L.ventricle
o Cardiac notch (deep indentation of superior lobe)
Left subclavian artery groove
Aortic impression (arch, descending)
Has 2 lobar (secondary) bronchi and 8 segmental bronchi (see the table of segments later)
Position of structures at the left hilum
Anterior inferior - 2 pulmonary veins
Superior posterior - 1 pulmonary artery (Artery is in Epibronchial
position)
Posterior Inferior - Left principle bronchus

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Borders of Lungs
1. Apex: 2 fingers above clavicle in mid-clavicular line
2. Anterior: from apex go down (parallel to the sternum) to 6th rib
3. Lower Border
a. Sternal line – 6th rib
b. Midcalvicular line – 6th rib
c. Anterior axillary line – 7th rib (the Lungs border is 1 rib level higher
d. Midaxillary line – 8th rib than the pleural border)
e. Posterior Axillary line – 9th rib
f. Scapular line – 10th rib
g. Paravertebral line - 11th rib
4. in the case of right lung, borders are the same, but when we descend from the apex, we
reach the 4th rib (or costosternal junction) then we make a little curve around the cardiac
notch after that we continue normally from the midclavicular line

Bronchopulmonary segments:

Segments of Lungs: morphological, functional, pathological and surgical units of the lung. The
largest subdivision of lobes, pyramidal shaped, has apex and base.

Apex facing lung hilum and base facing pleural surface

Separated from adjacent segments by connective tissue septa
Segmental bronchus (+ tertiary branch of pulmonary art) run in center of segment
Inside CT septa separating segments we find Pulmonary veins and lymph vessels running
towards hilus (intersegmental parts of veins)
Usually 18 in number (R. lung has 10, L. lung has 8 usually because 1+2 fused
together & cannot be separated surgically, and the medial basal segment is absent)
Segments are surgically resectable / removable
Segment is composed of smaller units lobules
Lobules also pyramidal shaped, inside them Bronchiole
One lobule belongs to 1 terminal bronchus which is branching inside lobule forming
bronchioli (no cartilage, no glands but smooth muscle)

Right Lung Left Lung

1) Apical segment 1+2) Apico-posterior
Superior
2) Posterior segment segment (Apical &
Superior Lobe division
Superior posterior fused together)
3) Anterior segment Lobe 3) Anterior segment
Inferior
4) Lateral segment 4) Superior Lingular seg.
Middle Lobe division
5) Medial segment 5) Inferior Lingular seg.
6) Superior (apical) seg. 6) Superior (apical) seg.
7) Medial basal seg. 7) Absent
Inferior Lobe 8) Anterior basal seg. Inferior Lobe 8) Anterior basal segment
9) Lateral Basal seg. 9) Lateral basal segment
10) Posterior basal seg. 10) Posterior basal seg.

* On the surface of the lung 1-2 cm areas bordered by black color (surrounded). These areas
are lobules (base). Black area pollution inside CT phagocytic work (Anthracosis)

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* Bronchopericardial membrane: central CT membrane that firmly attach root of lung and
tracheal bifurcation to posterior wall of pericardium, into the tendinous center of diaphragm.
Forms partition between middle and posterior Mediastinum

Bronchial tree: Main bronchus

Lobar bronchus

Segmental bronchus

20 Generations & branches

Terminal bronchi

Bronchiolus (no cartilage)

Lobes
Segments Respiratory bronchioli
(Terminal)

Lobules Alveolar ducts

Pulmonary
Acini Alveolar sacs

Pulmonary Alveolus

*the lobules are subunits of the bronchopulmonary segments

Vasculature of lungs: Double circulation (functional + nutritive)

A) Pulmonary trunk:
a. Extends upwards from the conus arteriosus of RV of heart, and carries poorly
oxygenated blood to the lungs for oxygenation
b. Passes superior and posterior from the front of the ascending aorta to its left side
about 5cm and bifurcates into R. & L. Pulmonary arteries at sternal angle of
Louis
1. RPA: Deoxygenated blood to right lung runs horizontally towards the hilus
of R. Lung under aortic arch, behind ascending aorta and SVC. Anterior &
under the right bronchus
2. LPA: shorter and narrower than RPA, arches over the L. pulmonary bronchus
Connected to aortic arch by ligamentum arteriosum (remnant of Ductus
arteriosus of Botalo)
B) Pulmonary Veins:
2 on each side, oxygenated blood into the Left Atrium
Are intersegmental (between segments, in the CT space) in drainage not
parallel with art. / bronchi)
Carry oxygenated blood from respiratory part of bronchioles (alveoli) and
deoxygenated blood from visceral pleura

C) Bronchial arteries:
Supply oxygenated blood to the non respiratory conducting tissues of the lung
(root, hilum) and visceral pleura
Anastomose with pulmonary artery

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2 L. bronchial arteries + 1 R. bronchial artery Usually arise directly from

aorta or maybe from upper posterior intercostal arteries
D) Bronchial Veins:
Drain part of lungs supplied by bronchial arteries
R. bronchial vein drains into Azygos vein
L. bronchial vein drains into Accessory hemiazygos or sup. Intercostals vein
on L.side
The also receive blood from esophageal veins

Lumphatic drainage of lungs:

Drain bronchial tree, pulmonary vessels and CT septa
Superficial (sub-pleural) Lymph plexus into bronchopulmonary nodes
(Hilar lymph nodes)
Deep lymphatic plexus (Submucosa of bronchi) and CT into pulmonary
lymph nodes (along lobar branches)
Superficial + deep into tracheobronchial nodes (sup. / inf.) around
bifurcation of trachea into Bronchomediastinal lymph nodes/trunks. Right
R. lymphatic duct, Left Thoracic duct , finally into Venous angle

E) Nerve supply of lungs:

Pulmonary plexus: Aff. + eff. (Parasympathetic) from CN-X + branches of
sympathetic trunk and cardiac plexus accompany BV and bronchi into the
lung
Effects:
1. SYM dilute lumen of bronchi + constrict vessels
2. PARA dilated vessels + constrict bronchi + secretion
Phrenic nerve: mediastinal pleura
Intercostals nerves: costal + diaphragmatic pleura

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Gross anatomy of the retro-

peritoneal organs

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The Kidneys
The kidneys are of the paired organs that excrete urine by removing excess water, salt and
wastes of protein metabolism from the blood while returning nutrients and chemicals back. They
are bean-shaped reddish brown organs (about 11 cm long, 5 cm wide, and 3 cm thick) lying on
either side of the vertebral column, retroperitonealy.

Position and orientation of kidneys:

The right kidney is a little lower than the left because the liver presses it down.
Positioned at the level of Th12-L3. The superior pole of the right kidney is crossed from
behind by the 12th rib.
The left kidney is positioned at the level of Th11-L2. The 12th rib divides it into two
parts: a superior, smaller part (1/3), and an inferior, larger part (2/3).

They have anterior and posterior surfaces. The anterior surface is a little lateral; the posterior
surface is a little medial. So, they're not exactly in the frontal plane (obliquely placed to the
protrusion of lumbar vertebrae).
They have superior and inferior poles. Above the superior pole, sits the suprarenal glands.
On the medial border which is concave, we have the renal hilum. The lateral border is convex.

Relationships of the kidneys:

Inferioposteriorly: Quadratus lumborum muscle

Medially: Psoas major muscle
Superiorly: lumbar part of the diaphragm, suprarenal glands
Anteriorly:
o R. Kidney: Liver (separated from the R. kidney by the Hepatorenal recess or
Morrison's pouch), duodenum (2nd part), right colic flexure
o L. Kidney: Stomach, spleen, pancreas, jejunum, left colic flexure
The Subcostal nerve + vessels, ilioinguinal and iliohypogastric nerves descend
diagonally behind the kidneys

The kidneys are fixed to the abdominal cavity by 3 capsules:

1. Fibrous capsule: The innermost capsule which is directly on the surface of the kidney.
Between the fibrous capsule and the renal fascia, there are connective tissue fibers
through the adipose tissue. So, finally, the renal fascia is connected to the fibrous capsule
and the fibrous capsule to the kidneys.

2. Perirenal adipose capsule (Perinephric): adipose tissue that surrounds the kidney and
vessels up to the renal sinus

3. Renal fascia of Gerota: The outermost capsule which covers the anterior surface of the
kidneys, continues to the posterior layer at the lateral margin, and continues above the
kidneys. So, it is a closed capsule superiorly and laterally, but it is open inferiorly and
medially, where the renal fascia blends with vascular sheaths of renal vessels and
continues as the periureteric fascia over the ureters.
Medially, the anterior layer passes in front of the aorta and inferior vena cava, continues
to the other side (anterior surface) the posterior layer passes behind the aorta and inferior
vena cava.

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The anterior layer of the renal fascia is fused with the parietal peritoneum (superiorly it
continues under the diaphragm as the diaphragmatic fascia that forms the primary
attachment of the suprarenal glands). The posterior layer is fused with the transversalis
fascia. This is the most important support for the kidneys. Between the two layers, the
middle capsule, the adipose capsule, fills the space.

4. Pararenal fat body (paranephric): not a real capsule but a mass of Extraperitoneal fat of
the lumbar region laying behind the renal fascia, contain small collagen bundles

** The collagen bundles, renal fascia, perinephric and paranephric fat, the renal vessels
and ureter, hold the kidneys in a relatively fixed position; however its 3 cm mobile during
respiration

Renal hilum (hilus): is the depression on the medial border of the kidney through which the
segmental renal vessels and nerves pass and where the apex of the renal pelvis occurs.
Order of structures at the hilum:
o Anterior: Renal vein
o Middle: Renal artery
o Posterior: Ureter

The renal sinus: is the cavity of the kidney, filled with adipose tissue and surrounded by
renal parenchyma and containing the calices (lesser and greater), pelvis and the segmental
vessels embedded within. Due to the renal sinus the kidney appears hollow or C-shaped on cross
section. The adipose capsule continues into the sinus.
Sinus = cavity
Hilus = entrance of this cavity

Order of structures at the sinus:

o Anterior: 3-4 primary segmental branches of renal artery
o Middle: Renal pelvis
o Posterior: Renal segmental veins, with 1 primary segmental branch

The renal pelvis (Pyelos): flattened, funnel shaped expansion of the superior end of the
ureter, receives 3 major calices, which receive 3-4 minor calices each (so 9-12 total minor
calices), the renal papillae (apexes of renal pyramids) open into the minor calices.
(So: 1 ureter, 1 pelvis, 3 major calices, 9-12 minor calices per kidney)

On a frontal section of the kidney through the largest plane (pole to pole), we can distinguish:
Outermost layer is the fibrous capsule on the surface.
The next layer is called the cortex cortices (right below the fibrous capsule),
consisting of a narrow peripheral zone where the renal corpuscles are not visible.
Inside the cortex, there are striations called medullary rays (Stria medullaris
corticis), the center of the renal lobule, consisting of straight tubular parts; these may
be either ascending or descending limbs of the nephronic loop or collecting tubules
The cortex continues into the medulla as cortical columns (Renal columns or
Bertin's columns), which are the prolongations of cortical substance separating the
pyramids of the kidney
The next part of the kidney is the medulla, formed by the medullary pyramids. The
apical (papillae) openings are situated on the minor calyx. On the surface of the

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apex, there are tiny openings for the papillary ducts. It is called lamina cribrousa
because of these openings.

Kidney lobes: The kidney develops from lobes. One original renal lobe is composed of one
pyramid and a half of the cortical column (renal column) around it. Approximately 25-30
original lobes have fused with each other and open to one minor calyx. The lobes are visible on
the external surfaces of kidneys in the fetuses.

The kidney segments are regions of the kidney supplied by end arteries branching from the
renal arteries; they are named anterior inferior segment, anterior superior segment, inferior
segment, posterior segment, and superior segment.

Vasculature of the kidney:

- Renal arteries: arise as paired visceral branches from the abdominal aorta
immediately below the SMA (between L1 & L2). they enters the kidney through the
hilus and divides into:
Segmental branches: 4-5 branches that supply the anatomical segments of
kidney, they are end arteries and give off:
Interlobar arteries: which run in the middle of the Bertin's columns, and
give rise to:
o Arcuate arteries: curved arteries at the corticomedullary border
that give:
Interlobular arteries or Cortical radiate arteries: the
branches of the arcuate arteries of the kidney radiating
outward through the renal columns and cortex and supplying
the glomeruli as:
Afferent glomerular arteriole

The segmental arteries are: anterior inferior segmental, anterior superior

segmental, inferior segmental, superior segmental and posterior segmental (last
one originates from the posterior continuation of the renal artery, behind the renal
pelvis at sinus)

Uretral branches: for the upper 1/3 of ureter

Suprarenal branches (Given before the hilus)
Capsular branches

- Usually, an additional renal artery (accessory) supplies the superior or inferior pole
of the kidneys.

- Renal veins: large veins formed at the renal hilus by the merger of the segmental
veins anterior to the corresponding arteries; they open at right angles into the inferior
vena cava at the level of the second lumbar vertebra.
The left renal vein passes in front of the abdominal aorta across the midline because
the inferior vena cava is on the right. As a consequence of this asymmetry, the left
renal vein receives the left testicular vein or ovarian vein (gonadal veins), but the
right one does not.

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Lymphatic drainage of kidneys:

- The lymphatic vessels of the kidney form 3 substances: in the substance of kidney,
under the fibrous capsule and in the Perirenal fat
- 4-5 lymphatic trunks leave the hilum, joined by the capsular branches, following the
renal vein to the Lumbar (Aortic and Caval) lymph nodes
-
Innervation of the kidney:
- Renal nerve plexus, from the celiac, aorticorenal and superior mesenteric ganglia:
SYM: supplied by fibers from the abdominopelvic Splanchnic nerves
PARA: posterior Vagal trunk

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Kidney 1: A longitudinal section, B nephron and adjacent blood vessels; 1 renal papilla, 2 renal column, 3 capsule,
4 renal pyramid, 5 calyx, 6 ureter, 7 renal pelvis, 8 renal vein, 9 renal artery, 10 interlobar artery, 11 arcuate
artery, 12 interlobular artery, 13 interlobar vein, 14 cortex, 15 interlobular vein, 16 renal sinus, 17 arcuate vein, 18
medulla, 19 vasa recta, 20 loop of Henle, 21 collecting duct, 22 arcuate vein, 23 arcuate artery, 24 proximal
convoluted tubule, 25 glomerulus, 26 Bowman’s capsule, 27 distal convoluted tubule

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The Ureter
The muscular duct that conducts the urine from the renal pelvis to the bladder; it consists of an
abdominal part and a pelvic part, is lined with transitional epithelium surrounded by smooth
muscle, both circular and longitudinal, and is covered externally by a tunica adventitia
The ureter starts from the hilus of the kidney as the most inferoposterior structure of the hilus,
and radiographically, the ureter shows constriction at multiple sites which are potential site of
obstruction by kidney stones:
1. Junction of ureter and renal pelves
2. The next constriction is before it enters the pelvis, at the pelvic brim, when it runs in
front of the common iliac artery at its division into external and internal iliac arteries.
3. The last constriction is during the passage through the wall of the urinary bladder

Morphologically, the ureter is crossed by multiple structures which are:

1. The Psoas major muscle with genitofemoral nerve from superolateral to
inferomedial (first actual crossing, the ureter is on the muscle and nerve)
2. Testicular (M) or ovarian (F) artery and vein (ureter is behind).
3. Common iliac arteries, at the pelvic brim (ureter is in front)
4. The last crossing is in the lesser pelvis where it crosses the uterine artery (F) or the
ductus deferens (M). (Ureter is behind)

The ureter has an abdominal (longer) part and a pelvic part. The abdominal part has the first
crossing. The second crossing is exactly at the border of the abdominal and pelvic part. The
third crossing is in the pelvic part.

The ureter pierces the wall of the urinary bladder from lateral to medial and posterior to anterior.
So, this entrance is oblique. It forms the orifice of the ureter in the urinary bladder, and the
vesicouretral valve.

Arterial supply of the ureters: comes from the neighboring blood vessels, as delicate
branches:
- Renal arteries
- Testicular / ovarian arteries
- Abdominal aorta
- Common iliac arteries

Venous drainage of the ureters:

- into the renal and gonadal veins

Lymphatic drainage of the ureters:

- left or right lumbar (caval or aortic) lymph nodes and the common iliac lymph nodes
- internal iliac lymph nodes in the pelvic parts of ureters

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The Suprarenal glands (Adrenals)

A flattened, roughly triangular body positioned at the superior pole of each kidney, enclosed by
the renal fascia and attached primarily to the diaphragmatic crura; surrounded by connective
tissue and considerable amount of Perinephric fat.
They are separated from the kidney by a think septum (part of the renal fascia)

The shape of the 2 suprarenal glands is different:

- The right suprarenal gland is frengian cap shaped (pyramidal), contacting the IVC
anteromedialy, and the liver anterolaterally.
- The left suprarenal gland is crescent-shaped (Semilunar), related to the stomach,
spleen, pancreas and left crus of diaphragm

Each gland has a hilum where vessel, nerves and lymphatics enter the gland

Each gland is composed of 2 parts:

- Cortex: derives from the mesoderm, and secretes corticosteroids and androgens. Has 3
histological zones: Zona Fasciculata (Secreting mineralcorticoids), Zona Glomerulusa
(secreting glucocorticoids), Zona reticularis (Secreting Androgens)

- Medulla: mass of nervous tissue permeated with capillaries and sinusoids that derive
from the neural crest cells associated with SYM nervous system. The Chromaffin cells
of the medulla are related to the SYM ganglion (postsynaptic) neurons in both derivation
(neural crest) and function. These cells secrete catecholamines (mostly Epinephrine) into
the blood in response to Presynaptic signals

Arterial supply of suprarenal gland:

- Superior suprarenal arteries: 6-8 branches, from the inferior phrenic artery, the 1st
paired branch of the abdominal aorta
- Middle suprarenal arteries: 1 branch, from the abdominal aorta near the level of origin
of SMA
- Inferior suprarenal arteries: 1 branch, from the renal arteries

Venous drainage of suprarenal gland:

- Right suprarenal vein: short, drains into IVC
- Left suprarenal vein: long, joined by the inferior phrenic vein, into the left renal vein

Lymphatic drainage of suprarenal gland:

- lumbar lymph nodes, from the plexus deep to the capsule

Nervous supply of the suprarenal gland:

- celiac plexus, abdominopelvic (greater, lesser and least) Splanchnic nerves: myelinated
Presynaptic SYM fibers (T10-L1) for the Chromaffin cells in the medulla

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Subdivision and Topography of the Aorta

1. Ascending aorta: ascends behind the pulmonary trunk toward the right.
Branches: the left and right coronary arteries

2. Aortic arch: located in the superior mediastinum (Supracardiac mediastinum). Begins at

the level of sternal angle and arches posteriorly to the left passes anterior to the
trachea to reach the left side of trachea and esophagus arches over the root of the lung
continuous as descending aorta at the level of Th-4.

Related structures: ligamentum Arteriosus passes from the root of the left
pulmonary artery to the inferior concave surface of the arch.
Left recurrent laryngeal nerve hooks around the arch before it ascends back.

Branches (from anteromedial to posterolateral): Brachiocephalic trunk, left

common carotid, and left Subclavian arteries

3. Descending (thoracic) aorta: situated in the posterior mediastinum. It descends first on

the left side and then in front of the vertebral column. This part of the aorta terminates at
the level of the lower border of Th-12, entering the abdomen through the diaphragmatic
aortic hiatus.

Related structures: the thoracic aorta descends through the posterior mediastinum
against the left pleura, thoracic duct is running behind and right to it. It passes
behind the root of the left lung and then posterior to the esophagus, close to the
body of thoracic vertebrae.

Branches:
• Bronchial (two direct left branches and one indirect right from
Intercostal)
• Esophageal • Pericardial
• Mediastinal (to lymph nodes)
• Posterior intercostals (nine pairs from 3rd to 11th intercostals space)
• Sub-costal • Superior Phrenic (superior aspect of diaphragm)

4. Abdominal aorta: begins at the aortic hiatus of the diaphragm at the level of Th12
intervertebral disk and ends at L4 by dividing into two common iliac arteries. Throughout
its course, the aorta lies against the vertebral column (retroperitoneal).

Related structures: Anteriorly it is related to the omental bursa, pancreas, and left
renal vein, posteriorly, to the vertebral column. It lays on the right to the thoracic
duct, and the inferior vena cava

Branches:
o Non-paired branches:
Celiac trunk (Haller's triplet) (Th12)
Superior mesenteric (L1)
Inferior mesenteric (L3)

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o Paired branches:
Non-visceral paired branches:
o Inferior phrenic: inferior aspect of diaphragm, gives the
superior suprarenal arteries
o Lumbar (segmental branches)
o Median sacral

Visceral paired branches:

o Middle suprarenal (L1)
o Renal
o Gonadal (L2)

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The Inferior vena cava

The IVC is formed on the right side of L5 by the union of the two common iliac veins, below the
bifurcation of the aorta.
It is longer than the abdominal aorta and ascends along the right side of the aorta, passes through
the opening of the inferior vena cava in the central tendon of the diaphragm at the level of Th8
and enters the right atrium of the heart.

Receives the:
- Right gonadal v.
- Right Suprarenal v.
- Right Inferior Phrenic v.
(On the left side, these veins usually drain into the left renal v.)

- Left & Right renal veins

- 3rd and 4th Lumbar veins
- The three (left, middle and right) hepatic veins.
The middle and left hepatic veins frequently unite for about 1 cm before entering
the vena cava.

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The thoracic duct

Consequently, essentially all the lymphatic drainage from the lower 1/2 of the body (deep
lymphatic drainage below the diaphragm, and all superficial drainage inferior the level of
umbilicus) converges in the abdomen to enter the beginning of the thoracic duct.

The common iliac lymph nodes receive lymph from the external & internal iliac lymph nodes,
and then it passes to the right & left lumbar lymph nodes
Lymph from the alimentary tract, liver, spleen and pancreas passes along the celiac and superior
and inferior mesenteric arteries to the Preaortic lymph nodes (celiac & superior & inferior
mesenteric nodes) around the origins of the arteries from the aorta. Efferents from these vessels
form the Intestinal lymphatic trunks, which may be single or multiple.

The right & left lumbar (Caval and Aortic) lymph nodes lie on both sides of the IVC and aorta.
These nodes receive lymph directly from the posterior abdominal wall, kidneys, ureters, testes /
ovaries, uterus and uterine tubes. Through the inferior mesenteric and common iliac lymph nodes
they also receive lymph from the descending colon, pelvis and lower limbs. Efferent lymphatics
vessels from the large lumbar lymph nodes form the right and left lumbar lymphatic trunks.

The thoracic duct starts anterior to the bodies of L1-L2 vertebrae, between the right crus of
diaphragm and the aorta (in only a small proportion of people, it begins as a thin walled sac or
dilation called Chyle cistern, which may vary in size & shape)
The thoracic duct is formed by:
- right & left lumbar lymphatic ducts
- intestinal lymph trunk(s)
- a pair of descending thoracic lymphatic trunks (carry lymph from lower 6 intercostal
spaces)

The thoracic duct ascends through the aortic hiatus in the diaphragm into the posterior
mediastinum, where it lies on the anterior aspect of the bodies of the inferior 7 thoracic vertebrae
among the thoracic aorta on its left, the azygos vein on its right and the esophagus anteriorly. At
the level of Th5-Th6 it crosses to the left, posterior to the esophagus and ascends in the superior
mediastinum. It receives:
- Branches from the upper intercostal spaces of both sides through collecting intercostal
trunks
- Branches from the posterior mediastinal structures (posterior mediastinal nodes,
posterior intercostal nodes)
- Jugular trunk (draining lymph from left side of head & neck)
- subclavian trunk (draining lymph from the left upper limb)
- bronchomediastinal lymphatic trunks (draining the tracheobronchial, brachiocephalic and
parasternal nodes)

The thoracic duct usually empties into the venous system, near the union of the left internal
jugular and subclavian veins, the left venous angle (sometimes directly into the left subclavian
or at the origin of the left brachiocephalic vein)

So in summary, the thoracic duct drains all lymph from lower 1/2 of the body, left thorax, left
head & neck and left upper limb

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Celiac trunk (Haller tripod):

The first non-paired branch of the abdominal aorta, originating just below the diaphragm after the
aorta pierces it through the aortic hiatus at the level of Th-12, it has 3 main branches:

o Left gastric artery: ascends to esophageal hiatus in a semi-intraperitoneal position

first giving cardial branches to supply the cardia and abdominal portion of
esophagus, forming a fold of peritoneum called Gastropancreatic fold, and then
descends along lesser curvature to anastomose with R. gastric art.

o Splenic artery: the largest branch which has a tortuous course posterior to omental
bursa, anterior to left kidney and runs at the superior border of pancreas.
It reaches the hilum of spleen as the proper splenic artery through the Splenorenal
ligament together with the tail of pancreas and there it divides to 5-6 branches, but
since no anastomosis between them 3 vascular segments +2 avascular ones.
On its way it gives:
Pancreatic branches
o Dorsal pancreatic artery: for the head and body of pancreas, gives
also the inferior pancreatic artery
o Great pancreatic artery: for the body & tail of pancreas
o Artery of tail of pancreas
Short gastric arteries: four or five small arteries, passing via the gastrosplenic
ligament to the fundus of the stomach along the greater curvature
Posterior gastric artery: ascends retroperitoneally in posterior wall of omental
bursa toward gastric fundus to reach (and supply) the gastric wall via the
gastrophrenic fold
Left Gastroepiploic (gastroomental) artery: runs through the gastrosplenic
ligament, to reach the greater curvatures of stomach, there, it descends along it
to anastomose with the right Gastroepiploic artery, to supply the nearby region
of stomach and greater omentum.

o Common hepatic artery: usually has 3 main branches,

Proper hepatic artery: goes through the Hepatoduodenal ligament in an
anterior and medial position to reach the Porta hepatis, where there it divides
into right & left branches of proper hepatic artery supplying the right & left
lobes of liver respectively. The right branch will give the cystic artery to
supply the gallbladder.
Right gastric artery: runs on the lesser curvature anastomosing with the left
gastric artery to supply the pyloric portion of stomach. It can arise also as a
branch of the proper hepatic artery quite often.
Gastroduodenal artery: gives 2 branches,
o Right Gastroepiploic artery: runs on the right side of the greater
curvature of stomach to anastomose with the left Gastroepiploic artery
to supply the corresponding area on the stomach and great omentum
o Supraduodenal artery: for the 1st part of duodenum

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o Superior Pancreaticoduodenal artery: supplies the head of pancreas

with the nearby duodenum with its anterior and posterior branches.
This artery anastomosis with the inferior anterior & posterior
Pancreaticoduodenal arteries of the superior mesenteric artery around
the head of pancreas as the 1st or minor or lesser Riolan arc or
a
n
a
s
t
o
m
o
s
i
s

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Superior mesenteric artery:

The 2nd non-paired branch of the abdominal aorta, arising 1cm below the celiac trunk at the level
of L1 vertebra, and traveling anterio-inferior direction to pass below the neck of pancreas and
through the pancreatic notch. Due to this course, 3 structures can be located between the SMA
and abdominal aorta:
1. Left renal vein (can be compressed by the SMA in this region, leading to Nutcracker
syndrome)
2. Uncinate process of pancreas, hooking around and below the SMA
3. Inferior horizontal part of duodenum (can be compressed here by the SMA, leading
the superior mesenteric artery syndrome)

The SMA runs to the left of the SMV, and after passing through the pancreatic notch, it starts
giving off branches:
1. Inferior Pancreaticoduodenal artery: first branch of the SMA, givin on the upper border
of the 3rd part of duodenum. It divides into anterior & posterior branches that supply the

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head of pancreas and the surrounding duodenum, and anastomose with the superior
anterior & inferior Pancreaticoduodenal arteries (branches of the gastroduodenal, of
common hepatic of celiac trunk, forming the an anastomosis or arc between the celiac
trunk and SMA around the head of pancreas know as the Minor or lesser Riolan arc)

2. Intestinal arteries: They run nearly parallel with one another between the layers of
the mesentery, each vessel dividing into two branches, which unite with adjacent
branches, forming a series of arches (arterial arcades), the convexities of which are
directed toward the intestine.
From this first set of arches branches arise, which unite with similar branches from above
and below and thus a second series of arches is formed; from the lower branches of the
artery, a third, a fourth, or even a fifth series of arches may be formed, diminishing in
size the nearer they approach the intestine.
In the short, upper part of the mesentery only one set of arches exists, but as the depth of
the mesentery increases, second, third, fourth, or even fifth groups are developed.
(Arcades increase in number towards the ileum)
From the terminal arches numerous small straight vessels (vasa recta) arise which
encircle the intestine, upon which they are distributed, ramifying between its coats.
a. Jejunal arteries: 4-5 branches, less arcades, longer vasa recta, less fat in the
mesentery
b. Ileal arteries: 11-13 branches, more arcades, shorter vasa recta, more fat in the
mesentery

3. Ileocolic artery: lower terminal branch of the SMA, passes towards the right iliac fossa,
and then branches into:
a. 3 branches to the terminal ileum (ileac branches), anastomose with Ileal arteries
b. 2 branches to the cecum (anterior & posterior cecal)
c. 1 branches to the appendix (appendicular artery) that descends in the
mesoappendix
d. 1 branch to the ascending colon (Ascending Colic) and anastomose with the right
colic artery

4. Right colic artery: It passes to the right behind the peritoneum, and in front of the
testicular or ovarian vessels, the right ureter and the Psoas major, toward the middle of
the ascending colon. Often, the artery arises as a common trunk with the Ileocolic artery.
It gives:
a. Descending branch: anastomoses with the Ileocecal artery
b. Ascending branch: anastomoses with the middle colic artery
** Both branches supply the ascending colon

5. Middle colic artery: mostly supplies the transverse colon. It arises just below the
pancreas, and, passing downward and forward between the layers of the transverse
mesocolon, divides into two branches
a. The right branch: anastomoses with the right colic artery
b. The left branch: anastomoses with the left colic artery, a branch of the inferior
mesenteric artery, around the left colic flexure, forming the Greater / Major
Riolan anastomosis or arc.

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Inferior mesenteric artery:

The 3rd non paired branch of the abdominal aorta, at the level of L3, it gives:

1. Left colic artery: runs to the left behind the peritoneum and in front of the Psoas
major muscle, and after a short course divide into an ascending and descending
branches. The stem of the artery or its branches cross the left ureter and left gonadal
vessels.
a. The ascending branch crosses in front of the left kidney and ends,
forming the paraduodenal fold, and then passes between the two layers
of the transverse mesocolon, by anastomosing with the middle colic
artery (forming the 2nd Riolan arc discussed above)
b. The descending branch anastomoses with the highest sigmoid artery.

** From the arches formed by these anastomoses branches are distributed

to the descending colon and the left part of the transverse colon

2. Sigmoidal arteries: usually 2-3 in number, supplying the lowest part of the descending
colon (iliac colon), and the sigmoid (pelvic) colon. It anastomoses above with the left
colic artery and below with the superior rectal artery as the Sudeck critical anastomosis

3. Superior rectal artery (Superior hemorrhoidal artery): an artery that descends to the
pelvis within the Mesosigmoidium layers to supply the rectum. At the level of S3 it
divides into 2 branches, which descend on both sides of the rectum supplying mainly
the upper 1/3 of it. Anastomoses with the middle and inferior rectal arteries

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Gross anatomy of the heart

& mediastinum

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The Heart
A hollow fibromuscular conical organ that receives the blood from the veins and propels it into the
arteries, by repeated, rhythmic contractions. In mammals it is divided by a musculomembranous
septum into two halves—right or venous and left or arterial—each of which consists of a receiving
chamber (atrium) and an ejecting chamber (ventricle).
The heart of a vertebrate is composed of cardiac muscle, an involuntary muscle tissue which is found
only within this organ. The average human heart, beating at 72 beats per minute, will beat
approximately 2.5 billion times during a lifetime (about 66 years). It weighs on average 250 g to 300
g in females and 300 g to 350 g in males.

Location:
The heart is located in the thoracic cavity, in the inferior part of the anterior mediastinum or
so called cardiac mediastinum, below the supra-cardiac mediastinum. (See description of
mediastinum at the end)

2/3 of the heart is located to the left of the midline and 1/3 to the right. The heart has an:
- Apex: located at the level of the 5th intercostal space, 9 cm from midsternal line
- Base: (Basis Cordis) located at the 3rd costal cartilage level (2cm L., 1cm R.)

The heart itself is rotated 60º to the left in the sagittal axis, 30º up in the transverse axis and
15º to the left around the Heart axis.
o The heart axis is defined as a line passing between the middle of the spine of the
right scapula and the apex of the heart.

Surfaces:
- Sternocostal: Right atrium + right ventricle + small part of left ventricle
- Diaphragmatic: Mainly 2/5 right ventricle and 3/5 left ventricle + a small part of the
right atrium around the IVC
- Posterior (mediastinal): Mainly the left atrium, between the 4 pulmonary veins
orifices
- Pulmonary (right): Right atrium
- Pulmonary (left): Left ventricle, contacting the cardiac impression of the left lung

Anatomical Borders (Margins):

- Right: Long, formed by the
Right atrium above, atrial portion
Right ventricle below, thin and sharp, named the Acute margin, almost
horizontal
- Left: shorter, full and more round, formed by:
Left ventricle mainly, called the Obtuse (dull, not sharp)
Slightly by the left atrium above

* Note: for the radiological borders (margins) of the heart, please check the heart
X-ray section below

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Projections:
- Right superior point: at the 3rd rib, right side of sternum (entrance of SVC to right
atrium)
- Left superior point: at the 3rd rib, 3 cm left to the sternum (left superior end of
coronary sulcus)
- Right inferior point: 1 cm right to the 6th sternocostal joint, right side of sternum
(right lower end of coronary sulcus)
- Left inferior point: 5th IC space, 9 cm left of midline of sternum (apex of heart)

If we connect these 4 points with 4 arcuate lines we get: The Margin (borderline) of the
heart, which has:
- short axis: between superior left and inferior right points coronary sulcus plane (in
this plane we have the Fibrous ring of the heart (Anulus fibrosus)
- Long axis: Oblique, from superior right (posterior) to inferior left (anterior) means
that the apex of heart is closer to the chest wall than the SVC entrance to right atrium
(which means that the heart is rotated around its axis as we mentioned above)

Pericardium:
A fibrous sac that encloses the heart and the proximal parts of the great vessels and occupies the
cardiac mediastinum, It is composed of 2 main layers:
o Tough external parietal pericardium
o Visceral layer of serous pericardium (Epicardium)

1) Parietal pericardium:
- Continues with Tunica adventitia of the great vessels and leaves the heart via the
pretracheal layer of the cervical fascia, composed of an outer fibrous layer, and an
inner serous layer (mesothelial cells) that reflects on the proximal parts of great
vessels as the visceral layer of pericardium. It has got some connections:
The Sternopericardial ligament attaches to the posterior aspect of sternum
The Pleuropericardiac membrane attaches to the parietal pleura
Its connected to the central tendon of diaphragm by the Pericadiophrenic
ligament (strong adhesion)

2) Visceral layer of pericardium:

- is reflected onto the heart and great vessels as the visceral layer of serous pericardium
(Epicardium)
Arterious reflections: at division of pulmonary trunk and beginning of the
aortic arch, so the 10-12 cm of the aorta + pulmonary trunk are inside the
pericardiac cavity
Venous reflections: on the SVC at the entrance of the azygos veins into it (so
1/2 SVC in and 1/2 out). Also all the thoracic IVC which is ~1cm is totally
inside the pericardium

Together with the reflection on the pulmonary veins as well, the venous
reflections form the so called Sappey's T (T-shaped reflections of the
pericardium, horizontal T)

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Pericardiac Sinuses:

During embryonic development, the heart tube is initially straight down with the venous end
being below and the Arterious end above.
The venous end will migrate upward and behind the Arterious end and forms a U-shaped tube
which will give the venous reflection at the bending of this tube.

- Transverse Pericardiac sinus: found between main arteries (Aorta and Pulmonary
trunk) and main veins (Pulmonary veins and SVC) reflections. Its an Open sinus
Surgically important sinus because it allows the surgeon to pass his fingers in, and
applies a ligature to stop the circulation for example in heart transplantation surgeries

- Oblique Pericardiac sinus: located at the venous reflections only (R. and L.
pulmonary veins and IVC) behind the heart, after lifting the apex, between the
parietal and the visceral layers. It’s a blind recess with a dead end at the inferior part
of Sappey's T. It's reached from the left side by 45º

Arterial supply of the pericardium:

Mainly the Pericardiophrenic artery (branch of the internal thoracic artery)
Musculophrenic artery (also from the internal thoracic artery)
Superior Phrenic arteries (branches of thoracic aorta)
Coronary arteries (only to the visceral layer)

Venous drainage:
Pericardiophrenic vein to the brachiocephalic veins
Azygos venous system

Nervous supply of the pericardium:

Phrenic nerve: Sensory innervation (reflected to ipsilateral skin dermatomes
C3-C5)
Sympathetic trunk (vasomotor)

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Layers of the heart:

3 main layers: 1) Epicardium: Visceral layer of the pericardium
2) Myocardium: muscular layer
3) Endocardium: innermost endothelial layer

But if we start from the outermost layer of the heart including the pericardium we have:
1) Outer fibrous layer of parietal pericardium
2) Inner serous layer of parietal pericardium
3) Visceral pericardium (Epicardium): the fat (pericardiac adipose tissue) will
accumulate between this layer and the next myocardium layer. The coronary arteries
run inside this fat between the 2 layers as well
4) Myocardium: originates and inserts on the fibrous skeleton of the heart with the
muscular hooks, has 3 layers in the ventricles:
1. Outer (external) oblique or longitudinal layer: subepicardiac; originates from
the AV valves fibrous rings to the apex, Anticlockwise and it forms the
Vortex of heart, and turns inward to form the innermost layer.
2. Middle circular layer: parallel to the coronary sulcus plane, NOT found at
apex (vortex)
3. Internal (innermost) longitudinal layer: subendocardial, its actually the
continuation of the outer (External) longitudinal at the vortex of the heart
internally, tot form the Papillary muscles and the Trabeculae Carnea

The atria have only 2 layers:

1. Outer Circular layer: extending over both atria, thicker anteriorly
2. Inner longitudinal layer: containing loops or annular fibers that pass to the
respective AV orifice or surround veins openings

5) Endocardium: a thin internal layer composed of an endothelium + subendothelial

connective tissue that form the valves (the valves are basically a duplication of the
endocardium).

** The Pericardial cavity (space) is a potential space between the parietal & visceral layers of
the pericardium. Normally it contains a thin film of serous fluid that lubricates the serous
surfaces and allows free movement of the hearth within the pericardium

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External Features of the heart:

When looking at the heart externally we can distinguish:

- Surfaces of the heart (Anterior, Inferior, Pulmonary)

- Chambers of the heart (RA + auricle, RV, LA + auricle, LV) separated by the
Coronary and Interventricular sulci, containing the cardiac veins and coronary
arteries:
The coronary (atrioventricular) sulcus: a groove running around the heart,
separating the atria from the ventricles
The anterior interventricular sulcus: interventricular sulcus anteriorly,
The posterior interventricular sulcus: interventricular sulcus posteriorly, in
which the middle cardiac vein runs with the posterior IV branch or RCA

** The interventricular sulci join the coronary sulcus at a right angle; posteriorly
it’s called the Cross of heart (Crux Cordis)
**Waterston’s groove: between the right pulmonary veins and the right atrium

- Great vessels:
Aorta: arising from the LV as the ascending aorta, then the aortic arch forming
(with its branches: Brachiocephalic trunk, L. common carotid and
L.subclavian) and crossing over the pulmonary trunk, and after becoming the
descending aorta posteriorly
Pulmonary trunk: arising from the RV, anterior to the aorta, then it winds
around and goes under the aortic arch and bifurcating into R. and L.
pulmonary arteries that enter the root of the R. and L. lungs respectively
Superior Vena Cava (SVC): formed by the R. and L. brachiocephalic trunks
Inferior Vena Cava (IVC): entering the inferior aspect of the RA
Pulmonary veins: 2 right and 2 left opening horizontally into the LA

** the Ligamentum arteriosum: a short band which remnant of fetal ductus

Arteriosus (Botalo duct) can be found between the inferior aspect of the aortic
arch and the superior aspect of pulmonary trunk, medially to it, we can find the R.
recurrent laryngeal nerve arching below the Aortic arch
** Sulcus terminalis Cordis: a groove separating the venae cavae from the base
of the right auricle

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Cavities / Chambers of the heart:

1) The Right Atrium:

- Forms the right border of the heart and part of it's anterior surface
- Has 2 main parts:
1. R. Auricle: rough muscular unfunctional anterior wall, composed of pectinate
muscles that develops from the common atrium
2. Atrium proper: smooth, thin walled posterior part (sinus venarum cavarum)
that develops from the Sinus venosus. Have openings for veins in it

** Both parts are separated externally by the Terminal sulcus (shallow vertical
groove from the superior to the inferior vena cava) and from the inside by the
Crista terminalis (well defined muscle bundle like a ridge) which develops from
the septum sporium.

- IVC orifice: on the lateral side. Has a Eustachian valve (guides the blood from IVC
towards the oval foramen to Left atrium in fetal life. In adults this valve has no
function. This orifice is at 5th costal cartilage level
- SVC orifice: has no valve. Opens at the level of the 3rd costal cartilage
- Coronary sinus orifice: located between the IVC orifice and the oval fossa. Has a
Thebesian valve. It collects blood from all cardiac veins except the anterior small
branches.

- Interatrial Septum: Have the Oval fossa + Limbus, which a depression in the wall
covered by a valve called the valve of the oval fossa. During the embryonic period it
was the Oval foramen. After birth, the valves fuse with the Limbus of oval foramen
closing it. If remains open after birth it's called Patent oval foramen or Foramen
apertum and plays a role in dangerous Venous-Areterious shunts that might cause
paradoxal embolism formation.

- Invisible to the naked eye, inside the right atrium we have the SA (Sinoatrial) node,
that is located at the upper end of the terminal sulcus near the SVC inlet in a
subepicaridiac position

- Koch triangle: a triangular area of the wall of the right atrium of the heart that marks
the approximate situation of the AV node, it is bordered superiorly by the tendon of
Todaro, inferiorly by the tricuspid valve annulus and posteriorly by the Thebasian
valve of the coronary sinus

- Sinus Septum: a small fold forming the medial end of the valve of the inferior vena
cava; it is developed from the dorsal wall of the embryonic sinus venosus

- Todaro Tendon: an inconstant tendinous structure that extends from the right fibrous trigone of the
heart toward the valve of the inferior vena cava or Sinus septum. It runs intramyocardially to insert
into the right fibrous trigone but can be easily demonstrated by superficial dissection, to demarcate the
site of AV node (in the Koch triangular area)

- The Torus aorticus: is a normal slight bulge of the right atrial septum sited superiorly and anteriorly. It
is superior to the coronary sinus and anterior to the fossa ovalis. Formed by the posterior (non-
coronary) cusp and the right coronary cusp of the aortic root lean against the medial right atrium.

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2) The Right Ventricle:

- Forms the largest part of the anterior surface of heart, a small part of the
diaphragmatic one and the inferior border.
- The ventricles are described in terms of 3 parts :
1. An inlet (Inflowing part): containing an atrioventricular valve and its tension
apparatus receiving venous blood from Right atrium
2. A trabecular body
3. An outlet (Outflowing part): supporting an arterial valve, blood flows out from
ventricle through the orifice of pulmonary trunk (infundibulum)

- This division is not meant to indicate that ventricular inlet and outlet portions lack
trabeculations, although in many places they do have smooth walls. Rather it
indicates that the apical trabecular zones are the most trabeculated and most
distinctive atrioventricular valves is similar in each ventricle although distinctive
differences exist.

**So the ventricle is a V-shaped structure (a 140º angle is formed between 2

parts), the 2 parts are separated by the Supraventricular crest (a protrusion on the
interventricular wall/septum)

**The Outflowing part forms a cone on the outer surface Conus Arteriosus,
from where the pulmonary trunk starts (infundibulum is from inside) and it has a
smooth surface

- The interior of the ventricle has an irregular muscular elevations Trabeculae

Carnea or Rathke's bundles

- The Septomargional Trabeculae or the Moderator band is a unique big Trabecula

crania that transverse the ventricle from side to side and has 3 functions
Origin of the Anterior papillary muscle
Transmission of the right branch of the AV bundle (R. Tawara crus) to the
ventricular wall
Holds the walls of the ventricle, prevent over dilation

- The Tricuspid valve guards the right atrioventricular orifice (AV orifice) (surrounded
by 1 coronary filum of fibrous skeleton). The base of the valve's cusps are attached to
the fibrous ring, and the tip is attached like a parachute to the Cordae Tendinae, that
attach to the anterior, posterior and Septal papillary muscles

- Papillary muscles are conical/cylindrical muscular protrusions with bases attached to

the ventricular wall. 3 groups in the right ventricle:
Anterior papillary muscle: largest and most prominent, arises from the
supramargainal Trabeculae and attaches to the Anterior + Posterior cusps
Posterior papillary muscle: arises from the inferior wall of the right ventricle
and attaches to the Posterior + Septal cusps
Septal papillary muscle: usually small and infrequent, arises from the IV
septum. (its almost motionless because the IV wall is not moving during
contraction)

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- The interventricular septum: composed of muscular part and membranous part. It's
2-3 times thicker than the wall of the Right ventricle, and bulges towards the right
ventricle in the cross sections creating the Supraventricular crest. The membranous
part located superioposteriorly in the right ventricle is a thin membrane that is part of
the fibrous skeleton and attached to the Septal cusp of the tricuspid valve. (that’s why
this cusp is not really functional)

3) Left Atrium:

- forms most of the base of the heart (posterior surface), so it’s the only chamber that
cannot be seen on normal X-ray
- Has 2 main parts:
1. L. Auricle: rough muscular unfunctional anterior wall, composed of pectinate
muscles. It overlaps the Pulmonary trunk (it’s a remnant of the primordial
atrium)
2. Atrium proper: smooth, thin walled posterior part. Has openings for the
valveless pairs of the L. and R. Pulmonary veins conveying oxygenated blood
from the lungs

** Though there are no true valves at the junction of the pulmonary veins and
the left atrium, "sleeves" of atrial muscle extend from the left atrial wall
around the pulmonary veins for 1 or 2 cm and may exert a partial sphincter-
like influence, tending to lessen reflux during atrial systole or mitral
regurgitation

- Has a semilunar depression on the Interatrial wall Fossa ovalis

- Has a slightly thicker wall than the right atrium
- The left AV orifice (mitral) leads to the left ventricle
- Has a close relation with the esophagus which is important clinically:
contrast material can be applied in the esophagus + X-ray medially will show
the enlargement of the left atrium bulging into the esophagus which is not
seen in normal X-Ray
when using the esophagoscope danger of injury to the esophageal wall and
damaging the left atrium

4) Left Ventricle:

- forms the left surface (Pulmonary) + most of the diaphragmatic surface + apex if the
heart
- It comprises:
1. An inlet portion (Inflow part): containing the mitral valve and its tension
apparatus; receiving oxygenated blood from the Left atrium
2. An apical trabecular zone: characterized by fine trabeculations
3. An outlet zone (Outflow part): supporting the aortic valve, which is
incomplete posteriorly so that the aortic and mitral valves are in fibrous
continuity

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- It performs more work the right ventricle because the systemic circulation pressure is
higher; therefore it has a thicker muscular wall (1-1.5cm) than the right ventricle
(0.5cm).
- The inner surface is covered with Trabeculae Carnea that are finer and more
numerous than right ventricle
- It has an Anterio-Medial and a Posterio-Lateral papillary muscles larger than the ones
in the right ventricle and has a double leaflet Mitral (bicuspid) (with the same cusps
as the papillary muscles) valve guarding the AV-orifice

- As it transverses through the LV, the blood stream undergoes 2 right angle turns
180º direction change. This flow direction reversal takes place around the anterior
cusp of the mitral valve, which forms the border between the outflow and inflow
portions (no Supraventricular crest here).
The superioanterior part of the ventricle is a smooth outflow part reaching the Aortic
vestibule and orifice that is positioned in the right posteriosuperior part and
surrounded by a fibrous ring to which the Right + Posterior + Left cusps of the aortic
valve are attached.

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Fibrous Skeleton of the heart (Annulus fibrosus Cordis):

It’s a complex network of dense collagen forming: 4 fibrous rings (annuli fibrosi) that surround
the orifices of the valves, Right and left fibrous trigons (formed by the connections between the
rings) and the membranous part of the IV septum. It is found in association with the base of the
ventricles, i.e., at the level of the coronary sulcus;
Functions:
- Keeps the orifices of the AV and semilunar valves patent and prevents them from
being over distended by an increased volume of blood pumped through them
(reinforcement)
- Providing attachment for the leaflets and cusps of the valves
- Provides attachment for myocardium (myocardial hooks), when uncoiled
continuous ventricular myocardial band that originate primarily from fibrous ring of
pulmonary valve and mainly inserts on the fibrous ring of the aortic valve
- Forms an electrical "Insulator" by separating the electrically conducted impulses of
atria and ventricles so that they contract independently of the surrounding.
- Provides passage for the initial part of the AV bundle (His bundle) of the conducting
system via the right fibrous trigone
-
The area between the septal leaflet of the tricuspid valve, the anterior leaflet of the mitral valve,
and the posterior or non-coronary cusp of the aortic valve forms one part of the central fibrous
body (Right fibrous trigone). The remaining portion is made up of fibrous tissue connecting the
left aortic cusp and the anterior leaflet of the mitral valve (Left fibrous trigone).
1. Right trigone: between L. and R. AV ostia and Aorta
2. Left trigone: between Aorta and L. AV ostium

Fila coronaria: a threadlike like structures arising from the fibrous trigons and encircling
the nearby valves, from the left fibrous trigone arises 1 coronary filum, and from the right
fibrous trigone 3, to forma a complete fibrous rings around the AV valves.

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Conus Arteriosus tendon: a stripe of fibrous tissue structure that is situated between the
aortic root and pulmonary trunk. Extends upward from the right atrioventricular fibrous
ring and connects the posterior surface of the Conus Arteriosus to the aorta
Os Cordis (Cardiac bone): represents the right fibrous trigone in big animals like
ox/elephant, or the calcified tendon of Todaro

Valves:

The heart contains four cardiac valves: 2 semilunar and 2 atrioventricular. The two semilunar
valves, aortic and pulmonary, guard the outlet orifice of their respective left and right ventricles.
The two AV valves, mitral and tricuspid, guard the inlet orifice of their respective left and right
ventricles.

The four cardiac valves are surrounded by fibrous tissue forming partial or complete "rings"
(valve
anulus). These fibrous rings join to form the fibrous skeleton of the heart, to which also is
attached atrial and ventricular myocardium.

The distal two-thirds of the normal AV valve and all the semilunar valve are avascular

- The Cusped valves (Mitral, tricuspid) (AV) are composed of 2 (Mitral: Anteromedial,
Posterolateral) or 3 (Tricuspid: Anterior, Posterior and septal) cusps that have mesothelium

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on both surfaces (Duplication of the endocardium). Between the mesothelium layers we have
fibrous cutaneous tissue.

The cusps are attached to Chordae Tendinae Papillary muscles prevent flipping back
into atria.

Chordae Tendinae: Dense collagen tendinous strands running from the papillary muscles to
the leaflets of the atrioventricular valves (mitral and tricuspid).

- The Semilunar valves: both aortic and pulmonary has 3 cusps

Aortic: Posterior / Right / Left
Pulmonary: Anterior / Right / Left

The small space between attachments of adjacent cusps is called a commissure. Each
semilunar valve has three commissures. The three commissures lie equally spaced around
the aorta or pulmonary trunk, and the circumference connecting these points has been
termed the sinotubular junction, which may also be described as the portion of the great
vessel separating the sinuses of Valsalva from the adjacent tubular portion of the great
artery.
In the aorta a distinctive circumferential "hump" or line marks this junction, originally
described by Leonardo da Vinci as the "supraaortic ridge"

During diastole, the elastic recoil of Pulmonary trunk/Aortic wall forces blood back
towards heart, but cusps open up like pockets close orifice prevents regurgitation of
blood.

Each semilunar valve is composed of 2 major parts:

Pars Densa: lower part, less flexible and mobile
Pars Flaccida: upper more mobile portion of the valve, sub-composed of:
i. 2 Lunules: The thickened edge of each cusp in the region of contact.
ii. 1 Nodule (Body of Arantius): the apex of the angulated free edge is
thickened further.

So each semilunar valve has 6 lunules and 3 nodules. The nodules help in
tight closure of the cusps when they approach each other

Immediately superiorly to the cusps, the walls of the origin of the aorta and the
pulmonary trunk are slightly dilated forming a Sinus aortic/pulmonary sinuses
blood in them prevents the cups from sticking to the wall of vessel
The mouth of R. coronary artery is at the Right aortic sinus
The mouth of L. coronary artery is at the Left aortic sinus
No artery at the posterior aortic sinus (non-coronary sinus)

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Auscultation of the heart-valves:

- Aortic valve: 2nd IC space, right side of sternum (1-2 cm right to midsternal line)
- Pulmonary valve: 2nd IC space, left side of sternum (1-2 cm left to midsternal line)
- Tricuspid valve: 5th IC space, left side of sternum (2 cm from midsternal line)
- Mitral valve: 5th IC space, left side of sternum in the midclavicular line (9 cm left to
midsternal line) (at the apex of heart)
(Remember:
- Sternal line: vertical line on the edges of the sternum
- Parasternal line: a vertical line in the middle between the midclavicular
and sternal lines)
- Erb's point: 3rd IC space, 3cm to midline of sternum (general auscultation point for
all sounds) (Don't mix it with Erb's nervous point or Punctum nervosum)

**Note: the auscultation point of the tricuspid valve is according to the Oxford manual of
internal medicine, Oxford manual of medical examination, and Bates manual of clinical
examination, although it’s possible also to listen to the Tricuspid valve on the right side of the
sternum according to other sources, because the location of the tricuspid valve itself which is
directly behind the midline of sternum at the level of 5th IC space. So be ready to present both
points of view.

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Vasculature of the heart:

2 coronary arteries supply the heart; they arise from the aortic (Valsalva) sinuses (at the dilated
portion of the ascending aorta)
They supply the: Myocardium & Epicardium

- The Right coronary artery (RCA):

Arises from the right anterior aortic sinus runs in the coronary groove after passing
between the right atrium and the pulmonary trunk reaching the posterior aspect of the
heart to end up in the posterior interventricular groove
Branches:
Conus Arteriosus branch: for the conus arterious portion of the right ventricle
Ascending Sinoatrial (SA) branch: for SA node (in 60% of people)
Right marginal branch: right border of heart, but not to the apex!
Right atrial branch: for right atrium
Right ventricular branch: for right ventricle, but not totally, until 1cm from
anterior interventricular groove)
Atrioventricular nodal branch: for AV-node, given at the crux of heart
(Posteriorly)
Posterior interventricular branch: descends in posterior interventricular groove,
accompanying the middle cardiac vein, has perforating ventricular posterior
Septal branches for interventricular septum (for posterior 1/3 of IV septum)

- The Left coronary artery (LCA):

Arises from the left anterior aortic sinus as the main left coronary stem passes between
left atrium (auricle) and left side of the pulmonary trunk, runs into the coronary groove
and divides into 2 main branches:
Anterior interventricular branch (left anterior descending, LAD): passes along the
anterior interventricular groove until the apex of heart together with the great cardiac
vein (can anastomose with RCA), gives:
Anterior Septal branches: supply the anterior 2/3 of IV septum + the AV
bundle system
Adjacent parts of Left and right ventricles (adjacent to IV groove)
Lateral diagonal branch: for the anterior surface of the heart
Ascending Sinoatrial (SA) branch: for SA node (in 40% of people)

Circumflex branch: follows the coronary groove together with the coronary sinus
until the posterior surface of the heart, gives:
Left marginal artery: supplies left margin of the heart
Left atrial artery: for left atrium and auricle
Left posterior lateral branch: Left ventricle (back)

** Coronary artery dominance

The artery that supplies the posterior descending artery (PDA) (a.k.a. posterior
interventricular artery) and the AV-Node determine the coronary dominance:

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- If the posterior descending artery (PDA) is supplied by the right coronary

artery (RCA), then the coronary circulation can be classified as "right-dominant".
- If the posterior descending artery (PDA) is supplied by the circumflex
artery (CX), a branch of the left artery, then the coronary circulation can be
classified as "left-dominant".
- If the posterior descending artery (PDA) is supplied by both the right coronary
artery (RCA) and the circumflex artery, then the coronary circulation can be
classified as "co-dominant".

Approximately 70% of the general population are right-dominant, 20% are co-dominant, and
10% are left-dominant

Venous drainage of the heart:

1) Great cardiac vein: begins near the apex of heart, ascends in the anterior IV groove with the
anterior IV branch of the LCA, after it goes left with the circumflex branch into in the
coronary sulcus and then drains into the Coronary sinus
2) Middle cardiac vein: runs in the posterior IV groove, together with posterior IV branch of
RCA, drains finally in the coronary sinus
3) Small cardiac vein: runs with the marginal branch of RCA backwards until it drains into
coronary sinus
4) Posterior vein of the left ventricle: found on the posterior surface of the left ventricle, drains
to the coronary sinus
5) Oblique vein of left atrium (Marshal's vein): remnant of the embryonic L. SVC, under the
left auricle Posteriorly, drains into the coronary sinus
6) Anterior small cardiac branches: found on the anterior surface of the right ventricle and
drain into the right atrium directly! (not into Coronary sinus)
7) Least Cardiac veins (Venae Cordi Minimi): found on the anterior surface of the left ventricle,
drain directly into the left atrium directly! (causing a small un-significant shunt)

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** The coronary sinus is a wide venous channel on the posterior aspect of heart in the coronary
groove that collects the great, middle, small and oblique veins and drains them into the right
atrium, has Thebesian valve guarding its exit.

The Conducting system of the heart:

Coordinates the cardiac cycle of systole/diastole, highly specialized cardiac muscle cells and
conducting fibers for initiating impulses and conducting them rapidly

Starts with the pacemaker: the SA (Sinoatrial)(Keith-Flack) node, located sub-epicardially at the
junction of SVC and right atrium anterolaterally, near the superior end of sulcus terminalis, it
gives ~100 pulse/min
Impulses will travel in the walls of the atria by myogenic conduction through the internodal
pathways (4 bundles: anterior, middle, posterior and Bachmann's) and will reach the AV
(atrioventricular) (Aschoff-Tawara) node

The AV node located sub-endocardially at the posterior inferior region of the interatrial septum,
below the fossa ovalis, demarcated by a triangular area called Koch’s triangle. After passing
through the AV node, the impulse will go through the AV-bundle of His (fasicle) that arises from
the AV node and pierces the right fibrous trigone through the fibrous skeleton of the heart, which
is the only connection between the atria and ventricles

After piercing the right trigone, the impulse will travel in the membranous part of the IV septum,
and at the junction of the membranous and muscular part, the His bundle will separate into 2
bundle branches:
Right bundle branch or AV crus (Right Tawara crus): which curves downward and
enters the Septomarginal Trabecula
Left bundle branch or AV crus (Left Tawara crus): sub-divides into Anterior (which
gives the septal) & Posterior fascicles

The 2 crura ride on the IV septum then ramify into Purkinje fibers over the ventricle walls

So: SA node Interatrial fibers AV node His bundle Tawara crura (L. and R.)
Purkinje fibers

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Nervous Supply of the heart:

The heart is supplied by both Sympathetic and Parasympathetic fibers forming:
Super
Middle cardiac plexuses
Inferior

The superior Sympathetic fibers from the cervical ganglia of the Sympathetic trunk, the middle
ones from the stellate ganglion and the inferior ones from the thoracic ganglion (long
postganglionic fibers)

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The Preganglionic parasympathetic fibers from the Vagus nerve (synapsing on intramural
ganglia close to the surface of heart, in the coronary sulcus, giving rise to the short
postganglionic fibers), which also carries sensory fibers

** Note:
- The right Vagus nerve passes between the Right Subclavian vein and artery
- The left Vagus nerve passes between the aortic arch and the left Subclavian vein

- The right Vagus gives its recurrent laryngeal branch under the right Subclavian artery
- The left Vagus gives its recurrent laryngeal branch under the aortic arch

Both Vagi continue into the thorax passing behind the root of lungs, while the Phrenic nerves
which arise from the cervical plexus and enter the thorax passing on the anterior scalene muscles,
pass in front of the root of lungs

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Percussion of the heart:

Percussion is a method of diagnosis that relays on the resonance of the air/fluid/solid filled
cavities that will sound differently when tapping them with fingers
When percussing over an air filled cavity like the lung, we can hear resonance of the sound, but
while precussing over a solid area like over the liver or the heart we can hear dullness and when
percussing over an area of solid organ covered by an air filled organ like the lung covering the
superior border of the heart we can hear a sound in between tympani and dullness so this method
requires expertise and very good hearing

- Relative Dullness of the heart: starting within the air filled lung (1st, 2nd IC spaces) we go
down to the 3rd IC space, the resonance will become dull due to the fluid filled heart being
behind the heart
Relative dullness marks the upper border of heart

- Absolute dullness of the heart: we keep going down to the 4th, 5th IC spaces (on left side of
course) and the sound will be more dull because the lung doesn’t cover the heart here, the
heart is directly found behind the anterior chest wall so no resonance
The size of the absolute dullness of the heart gives the size of the Cardiac notch

Shadow of the heart (Silhouette / X-Ray of the heart):

How the heart will the look in an X-ray of the chest area, since its denser than the surrounding
lung tissue, the X-ray will not penetrate it leaving behind a shadow corresponding with the
shape, size and edges (protrusions) of the heart

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On a chest radiograph, the central mediastinum area is occupied by a large radio-opaque shadow
termed the central mediastinal shadow which is the anatomical location of the heart and great
vessels. If any heart disease is suspected, it is very important to carefully examine its size,
position and shape. Enlargement of the heart shadow might indicate the presence of a cardiac
problem such as heart failure following a myocardial infarction. However, the heart shadow is
variable in shape even in normal subjects, mainly due to the wide variation in body build of
different people. Additionally, respiration will also affect the heart shadow.

Using the image above as a key, examine the right border of the central mediastinal shadow.
In its superior parts, the right margin of the shadow represents the superior vena cava (1). This is
a large vein which receives blood draining from the upper part of the body ie head, neck, upper
limbs and part of the upper chest. Inferior to the superior vena cava, the border is formed by the
right atrium (2) of the heart.
Inferior to the right atrium, a small part of the inferior vena cava can sometimes be identified as
it enters the chest through the diaphragm, prior to returning blood to the heart (3).

Now look at the left border.

The left border of the central mediastinal shadow is formed superiorly by the prominent left
projecting shadow of the arch of the aorta (4), also known clinically as the aortic knuckle.
Immediately inferior to the aortic arch is a shadow formed by the left pulmonary trunk (5).
Lateral to this shadow, a larger white shadow within the lung field is the left pulmonary artery
(6) shadow.
In a more inferior direction, the left border of the central mediastinal shadow is composed of the
left margin of the heart shadow.
In its superior region, the heart shadow is formed by the tip of the auricle of the left atrium (7).
Below the auricular shadow, the border is represented by the left ventricle (8) of the heart.
The point where the cardiac shadow meets the diaphragmatic shadow is called the left
cardiophrenic angle (9).

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The Mediastinum:

The middle part of the thoracic cavity, separated from the pleural cavities by the mediastinal
layer of the parietal pleura. Anteriorly it's bordered by the sternum, posteriorly by the vertebral
column and inferiorly by the diaphragm.

Separated by the root of lung (below the root of lung, the pulmonary ligament and the
Bronchopericardial membrane continues the separation, (above it there is no boundary) into:

1) Anterior mediastinum, which is further divided into

a. Inferior: Heart, cardiac mediastinum
b. Superior: Supracardiac mediastinum
2) Posterior mediastinum
**Note: This division is the one favored by our department, so please use this although many
other divisions have been made which are also correct.

Another division by Moore suggests a Transverse thoracic plane/ line between Th-4 & Th-5 separating an:
1) Superior mediastinum

2) Inferior mediastinum, divided by the pericardium into:

a. Anterior

b. Middle, contains the pericardium and its contents

c. Posterior

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Supracardiac mediastinum, Layers from anterior to posterior:

1) Sternum bone
2) Thymus (Adipose remnant in adult): primary lymphoid organ, receives Anterior
Intercostal and Anterior mediastinal branches of the internal thoracic arteries
3) Layer of Veins:
a. Brachiocephalic veins: formed by behind the sternoclavicular joints by the union
of the jugular and Subclavian veins
i. Left Brachiocephalic: oblique & long (10-12cm) passes over the branches
of aorta. Into it drains the inferior thyroidal vein
ii. Right Brachiocephalic: straight and short (5cm)
b. Superior Vena Cava (SVC): on the right side of the superior mediastinum,
anterolaterally to the trachea The right Phrenic nerve lies between the SVC
and the mediastinal pleura
4) Vagus & Phrenic nerves (Vagus continues down behind the root of lung, while the
Phrenic in front of it together with the Pericadiophrenic a./v.)
5) Layer of Aortic arch & branches:
a. Ascending aorta: 2-3 cm in diameter, intrapericardial
b. Aortic arch: arches posteriorly and descends behind the root of L. lung on the left
side of Th-4 vertebral body. Has 3 main branches:
i. Brachiocephalic trunk: at the right sternoclavicular joint level, gives the
Right common carotid & the Right Subclavian arteries
ii. Left common carotid artery
iii. Left Subclavian artery
6) Trachea (root of lung, hilum) Anterior
7) Recurrent Laryngeal nerve
8) Esophagus Posterior (check next page)
9) Vertebral column

** The right Vagus enters the thorax anteriorly to the right Subclavian artery gives the Right
recurrent laryngeal nerve, which ascends between the trachea and the esophagus to the larynx.
After that the R. Vagus continues behind the root of lung and gives Pulmonary, esophageal and
cardiac plexuses
** The Left Vagus enters the thorax between the L. common carotid and the L. Subclavian artery.
It gives the recurrent branch under the Aortic arch and branches for the plexuses, after it
continues behind the root of lung

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Posterior Mediastinum layers, contents:

1) Thoracic Aorta:
a. Begins at L. side of Th-4 body until Th-12, surrounded by thoracic aortic plexus,
forms an impression on the Left lung.
b. Gives Esophageal arteries (2-5 branches)
c. Gives Bronchial arteries: usually from 2nd/3rd IC art. but also directly from aorta
d. Gives 9-10 paired Posterior Intercostal arteries
e. Gives Pericardial branches

2) Esophagus and the 2 Vagi nerves: R. side, the Vagus behind esophagus, L. sides in
front

3) Thoracic duct and lymph trunks:

Originates from Chyle Cistern in the abdomen, between azygos vein and thoracic aorta/
and esophagus on the thoracic vertebral bodies. At the level of Th-4/Th-5 it crosses to the
left and terminates into the Left venous angle. Collects:
1. Left jugular trunk
2. Left subclavian trunk
3. Left bronchomediastinal trunk

4) Veins/ Lymph nodes:

a. Post. Mediastinal lymph nodes
b. Azygos vein (R. side): forms a collateral pathway between IVC & SVC. Drains
the posterior walls of thorax/ abdominal. It arches over the superior aspect of R.
root of lung to join SVC, producing and impression on the L. lung
c. Hemiazygos vein: arises on the L. side by the union of L. subcostal and ascending
lumber veins. Ascends posteriorly To thoracic aorta until T9 vertebra, crosses to
the right, behind the thoracic aorta, thoracic duct and esophagus and joins the
azygos vein
d. Accessory hemiazygos: begins at medial end of 4th/5th IC spaces, descends on L.
side of vertebral column from Th5-Th8 and joins azygos or hemiazygos veins.

5) Nerves:
a. 2 sympathetic trunks (thoracic), lie parallel on the heads of ribs and vertebral
bodies
b. Lower Splanchnic nerves
1. Greater
2. Lesser
3. Least

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Topography of the thoracic

cavity

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Structure of thoracic cage:

o 12 thoracic vertebrae + Intervertebral disks

o 12 pairs of ribs (with angle) + sternum

o Superior thoracic aperture (thoracic inlet): narrow, borders:

Posterior: T1 vertebra
Lateral: 1st pair of ribs + cartilage
Anterior: Superior border of manubrium, Jugular notch
Contents:
1. Esophagus
2. Trachea
3. Dome of Pleura (Cupula): the dome-shaped roof of the pleural cavity
extending up through the superior aperture of the thorax surrounded by
the 3 scalene muscles like a tent (see the description about the lung
pleura, or endothoracic fascia)
4. Bifurcation of the brachiocephalic trunk into right subclavian and right
common carotid arteries
5. Left common carotid and left subclavian arteries
6. Left and right brachiocephalic veins (venous angles)
7. Internal thoracic and superior Intercostal arteries (and veins)
8. T1 anterior ramus (joining brachial plexus
9. Thoracic duct
10. 2 sympathetic trunks
11. 2 Vagi nerves
12. 2 Phrenic nerves (found on the anterior scalene muscle)

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o Inferior thoracic aperture: very wide, limited by the costal arch, borders:
Posterior: T12 vertebra
Posterolateral: 11th, 12th ribs
Anterolateral: Joined (common) costal cartilages of 7-10 ribs
Anterior: Xiphoid process (Xephosternal joint)

o Sternum: A long flat bone, articulating with the cartilages of the first seven ribs and
with the clavicle, forming the middle part of the anterior wall of the thorax; it consists
of three portions:
Corpus or body: the middle and largest portion of the sternum, articulating
with the 3rd -7th ribs
Manubrium: the upper segment of the sternum, a flattened, roughly triangular
bone, occasionally fused with the body of the sternum, forming with it a slight
angle, the sternal angle of Louis that marks the level of the second costal
cartilage (rib) for counting ribs or Intercostal spaces. Denotes level of aortic
arch, bifurcation of trachea, and T4/T5 Intervertebral disc
Xiphoid process: the cartilage at the lower end of the sternum

Vertebrae, IV disk, Ligaments:

o Vertebrae:
7 Cervical vertebrae:
1. C1: Atlas, C2: Axis
2. C3-C5: typical
3. C6: has carotid tubercle, anterior tubercle of transverse process
4. C7: prominent v., the spinous process called Processus Prominens
5. The transverse process has:

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o Anterior root: remnant of ribs

o Posterior root: really transverse process
6. Transverse foramina, Anterior/Posterior tubercles, groove for spinal
nerves, origin of scalene muscles
12 Thoracic vertebrae
1. Costal fovea: for ribs attachment
5 Lumbar vertebrae:
1. Transverse process composed of:
o Costal process
o Accessory process
o Mammilary process (on superior articular process)
Sacrum (fused 5)
Coccyx (fused 4)

o Intervertebral disk:
a disk interposed between the bodies of adjacent vertebrae, composed of:
1. Annulus fibrosus: outer fibrous part , a ring of fibrocartilage and
fibrous tissue forming the circumference of the intervertebral disk;
surrounds the nucleus pulposus, which is prone to herniation when the
annulus fibrosus is compromised/cracked with injury or age
2. Nucleus pulposus: a central gelatinous soft fibrocartilage portion of the
intervertebral disk; regarded as a derivative of the notochord

o Ligaments:
Anterior longitudinal ligament: wide fibrous band interconnecting the
anterolateral surfaces of the vertebral bodies, blending with the outer lamellae
of the intervertebral disks (loosely) as it passes between vertebra, stabilizes
the vertebral column

Posterior longitudinal ligament: fibrous band interconnecting the posterior

surfaces of the vertebral bodies; it narrows to pass between the pedicles and
spreads out to blend with the outer lamellae of the posterior aspect of the
annulus fibrosus of the intervertebral disks (strongly); forms the anterior wall
of the vertebral canal, in the cervical level it becomes the Tectorial membrane,
saves the IV disks in position

Ligamenta Flava: paired ligaments of yellow elastic fibrous tissue, which

bind together the laminae of adjoining vertebrae, forming the dorsal wall of
the vertebral canal between the vertebra or laminae (Arches); penetration of
the ligamentum flavum with a trocar during epidural or spinal puncture
produces a distinct feel (“pop”), letting the practitioner know that the tip of the
trocar has entered the epidural space.
Helps with the erection of vertebral column

Interspinous ligaments: bands of fibrous tissue that connect the spinous

processes of adjacent vertebrae
Supraspinous ligaments: the longitudinal fibrous band attached to the tips of
the spinous processes of the vertebrae; in the cervical region it is altered to
form the Nuchal ligament

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Intertransverse ligament: connect the transverse processes of adjacent

vertebrae

o Intervertebral joints, movements:

Anteflexion: mainly cervical and lumbar vertebrae
Retroflexion: mainly cervical and lumbar vertebrae
Lateralflexion: mainly thoracic vertebrae
Torsional movement: mainly cervical and thoracic vertebrae

Ribs:

o 12 pairs:
1-7: true ribs, have individual cartilage connection to the sternum
8-10: false ribs, common cartilage connection
11, 12: floating ribs, no cartilage
Each rib has: Head, Neck, Body (with inferior groove/sulcus) and a tubercle
on the angle between neck and body
Curvatures of ribs:
1. On the edge
2. On the surface
3. Torsional (in plane)

Due to the curvature of the ribs, we get a space that lies laterally on both sides
of the vertebral column called the Pulmonary groove of thorax (paravertebral
gutter)

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o Joints of the head of ribs:

Double chambered joints (except 1, 11, 12)
Each rib articulates with lower and upper borders of 2 adjacent vertebrae. The
disk is connected by intra-articular ligament of head of rib
The radiate, Stellate, or anterior costovertebral ligament connecting the head
of each rib to the bodies of the two vertebrae with which it articulates

o Costotransverse joints:
Between articular facet of costal tubercle and costal fovea of the transverse
process
Has the Costotransverse ligament that connects the dorsal aspect of the neck
of a rib to the ventral aspect of the corresponding transverse process (lateral
and superior)

o Sternocostal joints:
1, 6, 7: Synchondrosis, joined by cartilages
2-5: Synovial joints, enforced by radiate Sternocostal ligaments anteriorly
Interchondral joints: the synovial joints between the contiguous surfaces of
the 5-10 costal cartilages, forming the costal arch

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Muscles of the thoracic wall:

o Pectoralis major
o Pectoralis minor
o Subclavius Thoracoappendicular muscles that attach also to the limbs and
Serratus anterior function also as accessory respiratory muscles
o Latissimus Dorsi

o Scalene Muscles (Anterior, Middle, Posterior): important in deep inspiration

o Serratus posterior superior / inferior: function more in stabilization and
proprioception
o Levatorius Costorum: Vertebral movement and proprioception

o Intercostal muscles:
Superficial layer:
1. External Intercostal muscles:
o 11 pairs, occupy Intercostal spaces from the tubercles of the
ribs posteriorly until the costochondral junctions anteriorly
o Anteriorly they are replaced by the External Intercostal
membrane
o The fibers run from the lower sharp margin of the rib and
passes obliquely inferoanterioly to the upper border of the
lower rib (like the direction of your fingers when you put your
hands in your pocket)
o Function: contract during inspiration, elevate ribs and maintain
tone of the Intercostal space

Inner Layer:
1. Internal Intercostal muscles:
o 11 pairs, run deep at right angles with the external Intercostal
muscles
o Fibers run superioanteriorly from the inferior groove of the
upper rib to the upper margin of the lower rib
o Range from the sternum until the angle of the rib posteriorly,
where they are replaced by the internal Intercostal membranes
o Function:
Interossious part: during expiration, depresses ribs
Interchondral (intercartilaginous part): during
inspiration, elevates ribs with external Intercostals,
resist mediolateral movement

2. Innermost Intercostal muscles:

o Similar to the internal intercostals and essentially their deeper
parts, parallel to them. They are separated from the internal
intercostals by the Intercostal nerves and vessels in the
intercostal space (Neurovascular bundle, order from superior
to inferior: vein, artery, nerve)

3. Subcostal muscles (inconstant):

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o In the posterior lateral thoracic wall, same direction as the

internal Intercostals, but extends across more than 1 Intercostal
space
o Function: Expiration

Transverse thoracic muscles: attach on the lower part of the sternum and
xiphoid process internally in the thoracic cage, and insert superolaterally on
the 2nd-6th costal cartilages, function in Expiration (weak)

o Diaphragm: Main inspiration muscle

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Fascia of the thoracic wall:

o Pectoral fascia: bed of breast, covering the Pectoralis major

o Claviopectoral fascia: stretches from the clavicle, Coracoid process and extends
downward enclosing the Subclavius muscle then the Pectoralis minor (between them
it’s called costocoracoid membrane or ligament) and inferiorly it becomes continuous
with the Axillary fascia as the Suspensory Ligament of the Axilla, which supports the
Axillary fascia and pulls it with the skin upward, forming the Axillary fossa. The
Claviopectoral fascia divides the Deltopectoral triangle into 2 compartments:
Superficial & Deep.

The Superficial Pectoral fascia covers the Pectoralis major muscle, which continues
to the Axillary region to become the Superficial Axillary fascia (base-floor of
Axillary fossa with skin). The Deep pectoral fascia covers the Pectoralis major
muscle form the inside.

Note: please check the Netter atlas, Plate 428 for this fascia and its drawing

o Endothoracic fascia: lines the thoracic cage internally and attaches the adjacent
portion of the lining of lung cavities (Costal parietal pleura) to the thoracic wall
Towards the apices of the lungs it becomes more fibrous & thickened, and reinforces
the lung cupula as the Surpapleural membrane or Sibson’s fascia, that attaches from
inner border of the first rib to the transverse process of the 7th cervical vertebra
(through the upper thoracic inlet)

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** So if we sum up the layers at the dome of lung or cupula will be (from ext. to
int.):
- Deep cervical fascia
- Surpapleural membrane (Sibson’s fascia)
- Cervical pleura
- Visceral pleura
- Lung (Apex)

** And all these structures are enclosed by the 3 scalene muscles as the scalene tent, and
covered by the skin and subcutaneous adipose tissue

Nerves of the thoracic wall:

o 12 pairs of thoracic spinal nerves supply the thoracic wall, as soon as they leave the IV
foramina, the mixed spinal nerve divides into:
Anterior Ramus
Posterior Ramus

o Posterior Rami of the thoracic spinal nerves pass posteriorly, immediately lateral to the
articular processes of vertebrae to supply the muscles, joints and skin of dorsal thoracic
region. divide into:

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Lateral branch
Medial branch
Both of which will supply the deep (true) muscles of the back. The medial
branch of the dorsal primary ramus also supplies articular branches to the
Zygapophysial joints and the periosteum of the vertebral arch.

o The anterior rami of T1-T11 form the intercostal nerves that run along the extent of
the intercostal spaces
** Anterior ramus of T12 courses inferior to the 12th rib and known as the Subcostal
nerve

o 3rd – 6th IC nerves: enter the most medial part of posterior IC spaces, run initially
within the Endothoracic fascia between the parietal pleura and internal intercostal
membrane, in the middle of IC spaces.
Near the angle of ribs the nerve pass between the Internal intercostal and innermost
intercostal muscle in the costal groove (within the IC space), inferior to IC
artery/vein, on the inferior margin of the rib (below it)
Collateral branches arise also at the angle of rib, and run on the superior border of the
rib below

At the midaxillary line (MAL) it gives:

Lateral cutaneous
branches, divides into:
1. Anterior branch
2. Posterior branch
Near the sternum it turns anteriorly
between the costal cartilages and
become:
Anterior cutaneous
branches, that divides into:
1. Lateral branch
2. Medial branch

o Atypical intercostal nerves:

Anterior ramus of T1
divides into:
1. Large superior part: joins the brachial plexus
2. Small inferior part: 1st intercostal
** It has no cutaneous branches!

1st and 2nd intercostal nerves: course behind the ribs, not under them in costal
grooves
2nd intercostal nerve: has a large lateral cutaneous branch called
Intercostobrachial nerve formed at the 2nd IC space, in MAL that penetrates
the Serratus anterior muscle and enters the Axilla and medial aspect of arm to
anastomose with the Medial Brachial cutaneous nerve as the
Intercostobrachial anastomosis to innervate the skin of Axilla (importance in
breast surgery anesthesia)

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7th-11th IC nerves: after giving the lateral branch, they cross the costal margin
posteriorly, continue to supply the abdominal skin and muscles and become
the Thoracoabdominal nerves of the anterior abdominal wall

o So through the posterior ramus, the lateral and anterior cutaneous branches of its
anterior ramus, each spinal nerve supplies a slip like region Dermatome (The area
of skin supplied by cutaneous branches from a single spinal nerve)
Myotome: All muscles derived from one somite and innervated by one segmental spinal
nerve

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Vasculature of the Thoracic wall:

o Derived from:
Thoracic aorta: through the posterior Intercostal and Subcostal arteries
Subclavian artery: through the internal thoracic arteries and supreme
intercostal artery
Axillary artery: superior and lateral thoracic arteries

o So each IC space is supplied by 3 arteries:

Large posterior IC artery
A small pair of Anterior IC arteries

o Posterior IC arteries:
The 1st and 2nd IC arteries are given by the Supreme (Highest) IC artery, a
branch of the Costocervical trunk of the Subclavian artery
In the 3rd-11th IC spaces + the Subcostal artery of the Subcostal space, are
given as paired branches of the Thoracic aorta (Aortic Intercostals)
** Note: The right side arteries cross the vertebra and pass posterior to the
esophagus, thoracic duct, azygos vein, right lung and pleura

Each posterior IC artery has:

1. Posterior Ramus (branch): accompanies the posterior ramus of spinal
nerve to supply the spinal nerve, vertebral column, back muscles and
related skin
2. Collateral branches as in the case with the IC nerve
3. Anterior Ramus (branch): travels along the bottom of the rib, in the IC
space together with the corresponding vein and nerve, organized in
VAN fashion (Vein being most superior), supplying muscles and
related pleura
At the angle of ribs it gives the Lateral cutaneous branch that divides
into anterior and posterior sub-branches to supply the related
dermatome skin

Terminal and collateral branches anastomose with Anterior IC

branches anteriorly

o Internal thoracic arteries (Historically, Internal mammary arteries):

Arise at the root of neck, from the inferior surface of the Subclavian arteries at
their origin
Descends in the thorax behind the clavicle and 1st costal cartilage, crossed by
its origin by the ipsilateral Phrenic nerve
Descend on the internal surface of thorax slightly both sides lateral to the
sternum, posterior to the upper 6 costal cartilages, thus medial to the nipple,
running between the slips of transverse thoracic muscle
Branches:
1. Thymic branches

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2. Pericardicophrenic arteries: traveling with the phrenic nerve anterior

to the root of lungs, both sides of the pericardium
3. Sternal branches
4. Perforating branches
5. Mediastinal branches, bronchial
6. Direct Anterior IC arteries: 12 pairs, 2 in each upper 6 IC spaces,
traveling in the Intercostal space laterally, until anastomose with the
corresponding posterior IC arteries, supply also the pectoral muscles,
skin and breast
Terminate in the 6th IC space by dividing into
1. Superior Epigastric artery: medially travels downward into the
abdominal wall, anastomose with the inferior epigastric artery behind
the Rectus sheath, supplying the abdominal muscles, integument and
Falciform ligament
2. Musculophrenic artery: laterally and roughly follows the costal margin
to supply the 7th-9th IC spaces as the Indirect Anterior IC arteries to
supply the spaces and diaphragm

**Note: the inferior most 2 IC spaces don’t have Anterior IC arteries;

hence they are supplied by the Posterior IC branches totally

o Superior Thoracic artery: branch of the 1st part of Axillary supplying muscles of the
superior chest
o Lateral thoracic artery: branch of the 2nd party of Axillary, running down at the
lateral border of Pectoral muscles, supplying them, mammary glands and muscles of
chest

o Veins of the thoracic wall: 11 Intercostal veins, accompanying the IC artery, nerve,
laying most superior in the costal groove + 1 Subcostal vein
The veins of the 1st IC space are called Supreme Intercostal veins and they
drain into the nearby brachiocephalic vein
The most posterior IC veins drain into the Azygos/Hemiazygos venous system
2nd-4th IC veins form a trunk called: Superior IC vein
1. The Right Superior IC vein is the final tributary to the azygos vein
2. The left superior IC vein drains into the L. brachiocephalic vein,
passing along the L. side of the superior mediastinum and receiving
the L. Bronchial and Pericardicophrenic veins

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The Diaphragm
Double doomed musculotendinous partition between the thoracic and the abdominal cavities.
It is the chief muscle of inspiration, descending downward during deep breath
It has 2 main parts:

1. Muscular part, origin: subdivided into 3 parts,

a. Sternal part: 2 muscular slips attaching to the posterior aspect of the xiphoid
process
b. Costal part: attaching to the inner surfaces of the lower 6 costal cartilages and
their adjoining ribs on each side with muscular slips interdigitating with the
transverse abdominis muscle origin
c. Lumbar part:

Lumbar Part

Lateral crus Medial crus

Medial Arcuate ligament Lateral Arcuate ligament Right medial crus (L1-L4) Left medial crus (L1-L2)
(Lumbocostal) (Lumbocostal)

2 aponeurotic arches Muscular crura

2. Tendinous part, insertion: trifoliate central aponeurotic part, the Central tendon of
diaphragm, fused with the pericardium strongly with the Pericardiophrenic ligament

o The right medial crus is larger and longer than the left one, and although the esophagus is
found on the left side of the midline in the thoracic cavity, the esophageal hiatus in the
diaphragm is a formation of the right medial crus at the level of T10

o Over the anterior aspect of the Aorta, the 2 medial crura (L+R) unite together to form a
fibrous Median Arcuate ligament (T12 level)

o The right medial crus consist of 3 ligaments:

1 goes to the central tendon
1 arises from the median Arcuate ligament, forming the right border of the
esophageal hiatus
1 forming the left border of the esophageal hiatus

o The medial and lateral Arcuate ligaments are thickening of the fascia covering the Psoas
major and Quadratus lumborum muscles (anterior layer of the Thoracolumbar fascia)
Medial Arcuate ligament: from the left vertebral body of L1 to the transverse process
of L1, covers the Psoas major muscle

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Lateral Arcuate ligament: from the transverse process of L1 to the top of 12th rib,
covering the Quadratus lumborum muscle

o Apertures in the diaphragm:

Caval opening: at the level of T8/T9, for the passage of the IVC and some branches
of the right Phrenic nerve. The IVC is attached to this opening, so when the
diaphragm contracts its helps the blood flow in it
Esophageal hiatus: in the right crus, T10 level, for the passage of the esophagus and
the Anterior (L.) and Posterior (R.) Vagal trunks and esophageal tributaries of the
Left gastric vein (Coronary vein of stomach) (porto-caval anastomosis)
Aortic hiatus: at the level of T12, behind the median Arcuate ligament, for the
passage of aorta (thoracic becoming abdominal) and the thoracic duct
Sternocostal triangle / foramen: between the sternal and costal attachments,
transmits the superior epigastric vessel (branches of the internal thoracic arteries)
Between the Lateral and Medial crura: we have the intermediate hiatuses, through
which Sympathetic trunk, azygos (right side), hemiazygos (left side), greater & lesser
splanchnic nerves passes

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o Arterial supply of the diaphragm:

Superior Phrenic arteries: from the thoracic aorta
Inferior Phrenic arteries: from the abdominal aorta
Musculophrenic + Pericardiophrenic arteries: from the internal thoracic artery

o Innervation of the diaphragm:

Phrenic nerve (C3-C5) motor innervation, sensory also (Cut C4, breath no more!)

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Topography of the
abdominal wall & inguinal
region

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Fascia of the Anterolateral abdominal wall, layers:

o Superficial fascia:
Superficial layer of the superficial fascia (Camper’s fascia)
1. superficial portion of the subcutaneous tissue which is specialized for
fat storage and thus often has an abundance of fat, especially in the
overnourished individual, compared with the deeper, fibrous portion of
the subcutaneous tissue; in morbid obesity, this layer forms the core of
a large, sagging apron like fold
2. Continues over the inguinal ligament to merge with the superficial
fascia of thigh
3. Continues over the pubic and perineum as superficial layer of
superficial Perineal fascia

Deep layer of the superficial fascia (Membranous / fibrous fascia of Scarpa)

1. Attaches to the fascia lata just below the inguinal ligament
2. Continues over the pubic and perineum as the membranous layer
(Colle’s fascia) of the superficial Perineal fascia
3. Continues over the penis as the superficial fascia of penis and over the
scrotum as the Tunica Dartos (has smooth muscle)

o Deep fascia (Investing):

Has intermediate and deep layers
Covers the external aspects of the 3 muscles of the anterolateral abdominal
wall and their aponeurosis, cannot be easily separated or detached
The inner aspect of the abdomen is lined by the Trasversalis fascia
(contacting the trasversalis muscle)
Continues over the spermatic cord at the superficial inguinal ring as the
external spermatic fascia
Continues over the penis as the deep fascia of penis (Buck’s fascia) and over
the pubis and perineum as the deep Perineal fascia

o So if we sum up the layers of the abdominal wall, from outside to inside:

External
1. Skin
2. Subcutaneous fatty tissue
3. Superficial fascia
o Superficial layer of the superficial fascia (fatty Camper's
fascia)
o Deep layer of the superficial fascia (Membranous fascia of
Scarpa)
Middle
1. External oblique + aponeurosis
2. Internal oblique + aponeurosis
3. Transversus abdominis muscle + aponeurosis (on anterior surface)
Internal
1. Trasversalis fascia
2. Preperitoneal fatty tissue
3. Parietal peritoneum

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Abdominal muscles:
External Oblique

Fleshy digitations from the external surface of the lower 8 ribs (5th-12th), the
Origin
dorsal border is free
On the anterior 2/3 of the external lip of the iliac crest, on the inguinal ligament
Insertion
and on the outer (anterior) layer of the rectus sheath medially (linea alba)
Intercostal nerves (T8-T11), Subcostal nerve (T12), Ilioinguinal n.,
Innervation
iliohypogastric n.
Fibers direction is from Superolateral to inferomedial (Hands in pocket)
Muscle fibers become aponeurotic approximately at MCL and at the spinoum
line inferiorly
Maintains abdominal pressure to keep viscera in position Notes / function
Increases abdominal pressure,
Both sides flex the vertebral column,
One side bends it laterally and rotates it

Internal Oblique

Internal lip of the iliac crest, Thoracolumbar fascia, ASIS, lateral 2/3
Origin
of the inguinal ligament
Cranial part: Fleshy digitations to lower 3 ribs (10th-12th)
Middle part: on the linea alba, aponeurosis (anterior / posterior layers of rectus
sheath) Insertion
Caudal part: pubic tubercle, in males: spermatic cord as cremasteric muscle and
in females: reaches the round ligament of uterus
Lower 6 thoracic IC nerves, first lumbar nerves (Ilioinguinal, iliohypogastric) Innervation

Fibers spawn Inferolaterally to Superiomedialy (Hands on chest)

Maintains abdominal pressure to keep viscera in position
Increases abdominal pressure Notes / function
One side Bends the body laterally, and rotates it ipsilaterally
Flexes lumbar vertebral column (bends thorax forward)

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Transversus
abdominis
Internal surface of the lower 6 ribs (7th-12th), thoracolumbar fascia, internal lip of
Origin
the iliac crest, lateral 2/3 of the inquinal ligament
Xiphoid cartilage, Linea alba and, through the conjoint tendon, pubic tubercle and
Insertion
pectin pubis. Helps forming the posterior layer of the rectus sheath
Lower 6 thoracic IC nerves, first lumbar nerves (Ilioinguinal, iliohypogastric) Innervation

Maintains abdominal pressure to keep viscera in position,

Contraction and expansion of the abdominal wall Notes / function
Rotates and flexes the trunk

Rectus Abdominis

5th-7th cartilages of the ribs, Xyphoid process Origin

Pubic tubercle, crest and Symphysis Insertion

Intercostal nerves (T7-T12) Innervation

Anchored transversely by attachment to the anterior layer of the Rectus
sheath at 3 or more tendinous intersections, separating the muscle into
smaller parts
Notes / function
Flexes the vertebral column
Pulls the sternum (thorax) toward the pubis
Tenses the anterior abdominal wall

Pyramidalis

Pubic crest Origin

Lower Portion of linea alba Insertion
Intercostal nerves Innervation

Small triangular muscle, Tenses the linea alba, attachment is a surgical mark
Notes / function
median abdominal incision

Superficial abdominal muscles:

o Lateral group: External oblique, internal oblique, transversus abdominis muscles
o Medial group: Rectus abdominis, Pyramidalis

Deep abdominal muscles

o Quadratus lumborum, Psoas major / minor (See the discussion of the lumbar
dorsal region later)

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The Rectus sheath:

It’s a strong incomplete fibrous compartment of the rectus abdominis and pyramidalis muscles.
In it we can find also the epigastric arteries anastomosing, lymphatics and distal portions of the
Intercostal nerves (anterior rami of spinal nerves T7-T12)
The sheath is formed by the decussation of interweaving of the aponeurosis of the flat lateral
abdominal muscles.

Anterior layer of rectus sheath:

o Above Arcuate line: aponeurosis of external and internal oblique muscles
o Below Arcuate line: aponeurosis of external oblique, internal oblique and
transversus abdominis
Posterior layer of rectus sheath:
o Above Arcuate line: aponeurosis of internal oblique and transversus abdominis
muscles
o Below Arcuate line: rectus abdominis is in direct contact with Trasversalis fascia

** Arcuate line of Douglas (Semicircular): crescent shaped line marking the inferior
limit of the posterior layer of the rectus sheath just below the level of iliac crest

** Semilunar line of Spigelius: curved line along the lateral border of rectus abdominis
muscle, found on the aponeurosis of transversus abdominis muscle

** Linea Alba: a tendinous median raphe between the 2 rectus abdominis muscles,
extending from the xiphoid process to the pubic symphysis. Formed by the aponeurosis
of external oblique, internal oblique and transversus abdominis muscles

** Umbilical ring: a defect in the Linea Alba through which the fetal umbilical vessels
are passed to form the umbilical cord. All layers from the anterolateral wall fuse at the
umbilicus, and subcutaneous fat tissue accumulates postnataly raising the skin around it
(7-14 days after birth)

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Nerves of the Anterolateral abdominal wall:

o Thoracoabdominal
(Intercostal) nerves: distal,
abdominal parts of the
anterior rami of the inferior 6
thoracic spinal nerves (T7-
T11) (T10 is around the
umbilicus)
o Lateral thoracic cutaneous
branches of the thoracic
spinal nerves T7-T10
o Subcostal nerve: larger
anterior ramus of spinal
nerve T12
o Iliohypogastric nerve:
terminal branch of anterior
rami of spinal nerves L1-L2
o Ilioinguinal nerve: terminal
branch, with the
iliohypogastric nerve, the
first lumbar nerve, passes
through the inguinal canal
and superficial inguinal ring
to supply the skin of the
upper medial thigh, mons
pubis, and scrotum or labia
majora

Vessels of the anterolateral abdominal wall:

o Superior epigastric vessels: branches of the internal thoracic arteries enter the rectus
sheath superiorly through the posterior layer and supply the superior part of rectus
abdominis. Anastomose with the inferior epigastric vessels around the umbilical
region

o Inferior epigastric vessels: branches of the external iliac artery/vein just superior to
the inguinal ligament. Run superiorly in the trasversalis fascia to enter the rectus
sheath under the Arcuate line and form the Lateral Umbilical fold

o Superficial circumflex iliac vessels: branches of femoral artery and tributaries of

greater saphenous vein, they go laterally and up above inguinal ligament to
anastomose with the deep circumflex iliac vessels

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o Deep circumflex iliac vessels: branches of the external iliac artery, have the same
position as the inferior epigastric, but more laterally

o Superficial epigastric vessels: branches of femoral artery and tributaries of greater

saphenous vein, they go medially and up above inguinal ligament to anastomose with
the deep circumflex iliac vessels or external pudendal

o Cutaneous veins:
Paraumbilical veins: several small veins arising from cutaneous veins about
the umbilicus running along the round ligament of the liver, and terminating
in the portal vein. They constitute a porto-caval anastomosis and are subject to
varicosity during portal hypertension; varicose Paraumbilical veins form the
“caput medussae”
Thoracoepigastric veins: anastomosis between the superior epigastric vein
and lateral thoracic vein, many develop as altered venous flow
Inferior / Superior epigastric veins: may shunt blood in case if IVC block

Inguinal region:

Borders:
Superior: horizontal line from the ASIS to the midline
Medial: Linea alba
Inferolateral: inguinal ligament

Structures:
Internal wall: discussed later, the 5 umbilical folds with fossa between them
Externally: most important, Inguinal canal (vessels, nerves discussed previously also)

Inguinal ligament of Poupart: a fibrous band formed by the thickened inferior border of
the aponeurosis of the external oblique that extends from the ASIS to the pubic tubercle,
bridging muscular and vascular lacunae; forms the floor of the inguinal canal; gives
origin to the lowermost fibers of internal oblique and Transversus abdominis muscles.

Iliopubic tract: thickened inferior margin of the transversalis fascia seen as a fibrous
band running parallel and posterior (deep) to the inguinal ligament, contributing to the
posterior wall of the inguinal canal as it bridges the external iliac-femoral vessels from
the Iliopectineal arch to the superior pubic ramus. It marks the inferior edge of the deep
inguinal ring and the medial margin of the femoral canal. Seen only when the inguinal
region is viewed from its internal aspect, it is a useful landmark in laparoscopy of this
region, as for repair of inguinal herniae.

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Together the inguinal ligament and ilopubic tract function as the flexor retinaculum for the
hip joint, and this retinaculum spans the subinguinal hiatus, allowing passage of different
structures and subdividing it into compartments (see Subinguinal region for details). Some
fibers arise from the inguinal ligament as:
Lacunar ligament of Gimbernat: a curved triangular fibrous band that passes
horizontally backward from the medial end of the inguinal ligament to the
Pectineal line; it forms the medial boundary of the femoral ring (and Subinguinal
hiatus)
Pectineal ligament of Cooper: a thick, strong fibrous band that passes laterally
from the lacunar ligament, on the Pectineus muscle, along the Pectineal line of the
pubis. This fibrous tissue on the bony surface allows the purchase of sutures in
various procedures to repair inguinal herniae.
Reflected inguinal ligament of Colles: slightly reinforced portion of the external
oblique aponeurosis, formed by fibers derived from the medial portion of the
inguinal ligament of one side that run medially and slightly superiorly, defining
the inferior margin of the superficial inguinal ring; the fibers then pass on the
deep aspect of the ipsilateral medial crus, crossing the Linea alba and running
within the contralateral aponeurosis to course parallel and superior to the
contralateral inguinal ligament.
Iliopectineal arch / ligament: a thickened band of fused iliac and Psoas fascia
passing from the posterior aspect of the inguinal ligament anteriorly across the
front of the femoral nerve to attach to the iliopectineal eminence of the hip bone
posteriorly. The iliopectinal arch thus forms a septum which subdivides the space
deep to the inguinal ligament into a lateral muscular lacuna and a medial vascular
lacuna.
Inguinal Falx (conjoint tendon): common tendon of insertion of the Transversus
and internal oblique muscles into the crest and tubercle of the pubis and
iliopectineal line; it is frequently largely muscular rather than aponeurotic and
may be poorly developed; forms posterior wall of medial inguinal canal.

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Inguinal canal:
The obliquely, inferiorly and medially directed ~4cm passage through the
musculoaponeurotic layers of the lower anterior abdominal wall that transmits the spermatic
cord in the male and the round ligament of uterus in the female from the pelvic cavity to the
scrotum or labia majora, respectively.
We can imagine the canal as a long box with 6 sides (2 of which are openings),
So the canal has an:
Entrance, the deep inguinal ring: opening in the transversalis fascia in the lateral
inguinal fossa, through which the ductus deferens and gonadal vessels (or round
ligament of uterus in the female) enter the inguinal canal. Located midway between
anterior superior iliac spine and pubic tubercle, it is bounded medially by the lateral
umbilical fold (inferior epigastric vessels) and inferiorly by the Iliopubic tract.
Indirect inguinal hernias exit the abdominal cavity via the deep inguinal ring.

Exit, the superficial inguinal ring: slit-like opening in the aponeurosis of the
external oblique muscle of the abdominal wall through which the contents of the
inguinal canal emerge. Has a medial (Attached to the pubic crest) and lateral
(attached to the pubic tubercle) crura bordering its sides and connected by intercrural
fibers

Borders:
Superior wall (Roof):
Internal Oblique
Transversus
Abdominis muscle

Posterior wall: Anterior wall

Trasversalis Fascia Aponeurosis of External
Conjoint tendon oblique
(medial 1/3 only)
Inguinal canal
Aponeurosis of Internal
oblique (Lateral 1/3 only)

Inferior wall (floor):

Inguinal ligament

Contents if the inguinal canal:

In males: the spermatic cord and its coverings (including genital branch of genitofemoral
nerve) + the ilioinguinal nerve.
In females: the round ligament of the uterus (including genital branch of genitofemoral
nerve) + the ilioinguinal nerve.

** Note: The ilioinguinal nerve passes between the internal oblique and external oblique,
then behind the intercrural fibers of the Superficial Inguinal ring, passing through the
superficial ring to meet the spermatic cord and descend into the scrotum, so technically it
doesn’t run through the whole canal, only the most lateral part of it.

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Lumbar (Dorsal) Region:

Borders: Superior: Transverse line passing through the inferior angle of scapula
Lateral: A vertical line along the lateral border of abdomen
Inferior: Iliac crest
Medial: A vertical line between the spinous processes of corresponding
vertebrae

Skin Innervation:
Dermatome innervation (Segmental) (Dorsal cutaneous branches of T7-
L3)

Below the skin, we find the Superficial Lamina (Posterior) of the Thoracodorsal fascia
covering the most important structure which is the Latissimus Dorsi muscle (the broadest
muscle of the body) (Origin: spinous processes of thoracic T7-T12, Thoracolumbar fascia,
iliac crest and inferior 3 or 4 ribs, inferior angle of scapula, Insertion: Crest of Lesser
tubercle of Humerus with Teres Major).

Below the Latissimus Dorsi we should find the Thoracodorsal artery, vein and nerve
supplying the muscle, lying on the Serratus posterior inferior muscle.

Below the Thoracolumbar fascia, we can find the Erector Spinae muscle, External oblique
muscle and some fibers of the transverse abdominal muscle
The deepest structure below the Erector Spinae muscle is the Quadratus lumborum (below
the deepest lamina of the thoracolumbar fascia)

The Thoracolumbar (Lumbodorsal) fascia:

A deep investing membrane which covers the deep muscles of the back of the trunk,
it is made up of three layers:
- Anterior (thinnest)(Quadratus Lumborum fascia)
- Middle (Deep layer)
- Posterior (Thickest) (Superficial layer)

Two spaces are formed between these three layers of the fascia:
- Quadratus Lumborum space: between Anterior and middle layers
- Erector Spinae space: between middle and posterior layers

It contains both longitudinal and transverse fibers, and is attached, medially, to

the spinous processes of the thoracic vertebrae; laterally to the angles of the ribs
It Gives origin to internal oblique and Transversus Abdominis muscles, and Above, it
passes in front of the Serratus posterior superior and is continuous with a similar
investing layer on the back of the neck to become the Nuchal fascia.
In the thoracic region the Thoracodorsal fascia is a thin fibrous lamina which serves to
bind down the Extensor muscles of the vertebral column and to separate them from the
muscles connecting the vertebral column to the upper extremity.

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** Important structures to be found in this region also are 2 triangles: Petit Triangle & the
Auscultation triangle:

Triangle of Petit (Inferior Lumbar): a weak point of the wall so herniation occasionally
occur here, borders:
- Latissimus Dorsi muscle superiorly
- External oblique muscle laterally
- Iliac crest inferiorly
- Internal oblique muscle as the floor

Auscultatory Triangle (Superior Lumbar): the absence of musculature in this space

allows respiratory sounds to be heard clearly with a stethoscope, especially If the scapula is
drawn forward by folding the arms across the chest, and the trunk bent forward, borders:
- Inferior margin of trapezius superiorly
- Latissimus Dorsi inferiorly
- Vertebral margin (medial) of scapula laterally

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The Peritoneum and peritoneal coverings

The serous sac, consisting of mesothelium and a thin layer of irregular connective tissue, that
lines the abdominal cavity and covers most of the viscera contained therein; it is the largest
serous membrane of the human body; develops from the lateral plates of the mesoderm.
It forms two sacs: the peritoneal (or greater) sac and the omental bursa (lesser sac) connected by
the Epiploic foramen, and like any serosal covering it has 2 parts:
- Parietal peritoneum: lines the internal surface of abdominopelvic wall (sensitive to pain)
- Visceral peritoneum: Invests and covers abdominal and pelvic viscera/ organs
(insensitive)
The Abdominal and pelvic organs and structures -according to their peritoneal relations- can be
divided into 2 main groups:

A) Intraperitoneal: covered by peritoneum almost completely (like passing your fist into
an inflated balloon) (There is only one „really Intraperitoneal” located organ: the ovary -
which is situated within the peritoneal cavity)
- Semi-Peritoneal (used to be Intraperitoneal, then it got retracted back and
remained covered only on it 1/2)
B) Extraperitoneal (not surrounded by the peritoneum) – within this:
a) Retroperitoneal
b) Infraperitoneal
c) Preperitoneal structures

A) Intraperitoneal Organs:
1. Stomach
2. Duodenum (Sup. horizontal part only!!)
3. Liver – except bare area (Nude area)
4. Spleen
5. Jejunum
6. Ileum
7. Cecum (in some cases), appendix
8. Transverse colon
9. Sigmoid colon
10. Oviduct
11. Uterus (body + fundus)
Semi-Intraperitoneal organs:
1. Cecum (in some cases)
2. Ascending colon (Fig. D)
3. Descending colon (Fig. D)
4. Rectum - upper 1/3 (Fig. D)
5. Urinary bladder (when filled)
6. Post. Fornix of vagina

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B) Extraperitoneal organs, within this:

a) Retroperitoneal
Primary retroperitoneal:
1. Kidney
2. Adrenal gland
3. Ureter
4. Rectum – middle 1/3
Secondary retroperitoneal (originally intraperitoneal organs during their
development later lose their complete peritoneal covering and become
retroperitoneal):
1. Duodenum – from superior flexure to duodenojejunal flexure
2. Pancreas

Retroperitoneal structures also include:

l. Abdominal aorta and many of its primary and secondary branches
- e.g.: parietal branches: Inf. Phrenic a., lumbar arteries, middle
sacral a.
- Paired visceral branches: middle suprarenal a., renal a., gonadal
arteries
- Not primary branches: left gastric a., sup. + Inf.
Pancreaticoduodenal arteries, right colic a. (Jackson’s membrane),
left colic a.
2. Veins: IVC, common iliac veins;
Ascending lumbar veins, azygos/hemiazygos veins (their
beginning)
3. Lymphatics: lumbar trunks, the end of the intestinal trunk, Cisterna
Chyli
4. Nerves: lumbar and sciatic plexuses, sympathetic trunk, Para- and
prevertebral ganglia.

b) Infraperitoneal (primary):
1. Urinary bladder (if empty)
2. Rectum – lower 1/3
3. Prostate
4. Seminal vesicles
5. Vas deferens
6. Cervix of uterus
7. Ant. fornix of vagina
8. Urethra
9. Vagina

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Infraperitoneal structures include also

1. Common iliac arteries, ext. iliac a., some branches of int. iliac a.
2. Pelvic venous plexuses
3. Lymphatics: beginning of lumbar trunk; pelvic lymph nodes
4. Nerves: Pudendohaemorrhoidal plexus - sacral parasympathetic. nerves, pelvic
autonomic plexuses.

C) Preperitoneal:
The Preperitoneal space is located between the anterior parietal peritoneum and the
trasversalis fascia. Structures situated here cause 5 folds on the parietal peritoneum:
1. Median umbilical fold (unpaired): extends from the apex of urinary bladder to
the umbilicus and covers the median umbilical ligament, remnant of the urachus,
which joined the apex of fetal bladder to the umbilicus
2. Medial umbilical folds (paired): lateral to medial umbilical fold, cover the medial
umbilical ligaments, formed by the occluded parts of umbilical arteries
(remnants)
3. Lateral umbilical folds (paired): lateral to medial umbilical folds, cover the
inferior epigastric vessels can cause severe bleeding in case of cut

FSV: Supravesical fossa

FIM: Medial inguinal fossa (at the level of the superficial inguinal ring)
Hasselbach trigone (inguinal triangle)
FIL: Lateral inguinal fossa, lateral to lateral umbilical folds, including the
deep inguinal rings, potential site for indirect hernia

Going downwards, the preperitoneal space gets wider: supravesical and prostatic spaces
(and prevesical space of Retzius). Via the subarcuate hiatus the deep dorsal vein of penis
enters the vesical venous plexus.

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Embryology of the Peritoneum

Ventral and dorsal mesenteries (peritoneal duplications in front and behind) surround the
developing gut.

Ventral Mesentery:
The anterior peritoneal duplication exists only above the umbilical vein. Two parts can be
distinguished: ventral mesogastrium and ventral mesoduodenum.

A) ventral mesogastrium
The developing liver divides the ventral mesogastrium into smaller parts. The
derivatives of the ventral mesogastrium are:
1. The Falciform lig. of the liver (in the lower edge of it the remnant of the
umbilical vein forms the round lig. of the liver).
2. The Hepatogastric lig.
3-4. right + left coronary ligaments of the liver and left triangular lig. of the liver.

B) ventral mesoduodenum
The ventral mesoduodenum gives rise to the Hepatoduodenal lig.

Lesser omentum is formed by the Hepatogastric and Hepatoduodenal ligaments.

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Dorsal Mesentery:
The posterior peritoneal duplication develops in the whole length of the gut tube.

A) Dorsal Mesogastrium
The developing spleen divides it into:
1. Gastrosplenic lig.
2. Splenorenal lig. / Phrenicosplenic lig. / Pancreaticosplenic lig.

The distal part of the duodenum (between the sup. flexure and the duodenojejunal
flexure) is originally Intraperitoneal (Fig. A), but later becomes retroperitoneal
(secondary retroperitoneal organ).
During the fetal development the ascending and descending colon as well as the upper
1/3 of the rectum fuse with the posterior abdominal wall (Fig. B, C, D), only their
anterior part remains peritoneum-covered. These organs can be called Semi-
Intraperitoneal organs (Fig.D).

B) From the rest of the dorsal mesentery develop:

1. The greater omentum (4 layers). It later fuses with the 2 layers of the transverse
Mesocolon Gastrocolic lig. (6 layers)
2. The mesentery of the small intestines: fan shaped double fold of peritoneum that
suspends the jejunum and ileum from the posterior abdominal wall and transmits
nerve and blood vessels to and from the small intestine. Forms a root that
extends from the Duodenojejunal flexure to the R. iliac fossa (R. Sacroiliac
joint) and is about 15 cm long, contains the superior mesenteric and intestinal
vessels, nerves and lymphatics
3. The Mesoappendix: connects the appendix to the mesentery of ileum, contains
appendicular vessels.
4. The Transverse Mesocolon: connects the posterior surface of the transverse colon
to the posterior abdominal wall (pancreas), fuses with the greater omentum to
form the Gastrocolic ligament. Contains the middle colic vessels/nerves/lymph
5. The Mesosigmoidium: peritoneal fold that connects the sigmoid colon to the
pelvic wall and contains the sigmoid vessels. Line of attachment has a /\-shape.

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Subdivisions of peritoneal cavity

Omental bursa (lesser sac):
An extensive sac-like cavity that lies posterior to the stomach, lesser omentum and
adjacent structures. An irregular space, closed except for its communication with the
greater sac (See later) through the Epiploic (Omental, Winslow) foramen
It has 3 recesses:
- Superior recess: behind the stomach’s lesser omentum, and L-lobe of liver.
- Inferior (Omental) recess: behind stomach, extending into the layers of greater
omentum. Exists only in the fetal life, between the 2 duplications of the greater
omentum, later this will be obliterated (due to the fusion of the membranes of the
greater omentum).
- Splenic recess: extends left to the hilum of spleen, Bordered by the
Gastrosplenic and Phrenicosplenic (Splenorenal) ligaments.

Parts of the Omental bursa:

1) Epiploic (Omental, Winslow) foramen:

Admits two fingers, can be located by running a finger along gallbladder to the
free edge of lesser omentum.

Borders of the Epiploic foramen:

- Anterior: Hepatoduodenal ligament. (Portal triad)
- Posterior: Hepatorenal ligament + Inferior vena cava
- Superior: Liver (caudate lobe)
- Inferior: superior or first part of duodenum + Duodenorenal ligament

2) Vestibule: between the Epiploic foramen and the gastropancreatic fold

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3) Gastropancreatic fold (or diaphragma omentale): the narrowest part of the

omental bursa, separating the vestibule from the cavity proper. This fold is formed
by the left gastric a. and the coronary vein of the stomach (running behind the
peritoneum)

4) Cavity proper of the omental bursa:

Borders:
o Anterior: Hepatogastric ligament, stomach, Gastrocolic ligament
o Inferior: Transverse colon + Transverse Mesocolon
o Posterior: posterior parietal peritoneum + pancreas

Possible surgical entrances into the omental bursa (e.g. for pancreas surgery):
1) Via the lesser omentum
2) Via the greater omentum
3) Via the Transverse Mesocolon

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Greater sac (peritoneal cavity):

Extends across the entire breadth of the abdomen from the diaphragm until the pelvic
floor, the interior of the peritoneal sac, normally only a potential space between the
parietal and visceral layers of the peritoneum (filled with some peritoneal fluid for
lubrication – allowing movements of abdominal organs)
In males totally closed sac, in females the peritoneal cavity communicates with the outer
world via the oviduct – uterus - vagina.
It has recesses, which can be potential sites of internal herniae:
- Subphrenic (Suprahepatic, Hepaticophrenic) recess: separated into R. and L. by
the falciform ligament. It is the highest point of peritoneal cavity (air, gases can
be accumulated here in case of e.g. stomach perforation)
- Subhepatic recess or Hepatorenal (Morrison’s pouch): deep peritoneal pocket
between the liver anteriorly and the R. Kidney & suprarenal gland posteriorly.
Communicates with lesser sac via the Epiploic foramen and R. Paracolic gutter
- Paracolic recess (gutter): lays laterally to ascending colon (R. Paracolic gutter)
and laterally to the descending colon (L. Paracolic gutter)
- Rectovesical pouch – in males
- Rectouterine pouch (Douglas): the deepest point of the female abdominal
(peritoneal) cavity. Blood (e.g. from extrauterine gravidity!), inflammation fluid
can be accumulated here. The Douglas pouch can be examined without opening
the abdominal wall: by Douglas puncture (via the post. fornix of vagina).
- Vesicouterine pouch – in female
- Duodenojejunal, Sup. + Inf. Ileocecal, retrocecal, Paracolic recesses,
intersigmoid, iliac Subfascial recess.

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Omentum
A Double layered extension or fold of the peritoneum that passes from the stomach and proximal
part of the duodenum, to adjacent organs/ structures in abdominal cavity.

1. Lesser omentum:
Connects the lesser curvature of stomach and the proximal part of the duodenum to the
liver (fissure of ligamentum Venosum & Porta hepatica respectively)
Consists of Hepatogastric and Hepatoduodenal ligaments and forms the anterior wall of
the lesser sac of peritoneal cavity. Acts as a route for the Left and Right gastric vessels,
which run between the 2 layers along lesser curvature and anastomose there
Has a free margin containing the portal triad (inside the Hepatoduodenal ligament)

2. Greater omentum:
Hangs down like an apron from the greater curvature of the stomach and the proximal
part of the duodenum. After descending, it folds back and attaches to the anterior surface
of the transverse colon and its mesentery.
Derived from the embryonic dorsal mesentery, transmits the R. and L. Gastroepiploic
vessels along the greater curvature.
Consist of:
o Gastrolineal (Gastrosplenic) ligament: extends from the L. portion of greater
curvature of stomach to the hilum of spleen. Contains the Short gastric vessels
and L. Gastroepiploic vessels.
o Lienorenal (Splenorenal) (Phrenicosplenic) ligament: runs from hilum of spleen
to L. kidney. Contains Splenic vessels and the Tail of pancreas.
o Gastrophrenic ligament: from upper part of greater curvature of stomach to the
diaphragm, holds the cardia in position
o Gastrocolic ligament: from greater curvature of stomach to the transverse colon.

Peritoneal ligaments: a double layer of peritoneum that connects an organ with another organ
or the abdominal wall.

1. Phrenicocolic ligament (Sustentaculum lienis): runs from the L. colic flexure to the
diaphragm, form the splenic nest which holds the spleen in position
2. Falciform ligament: sickle shaped peritoneal fold, connects the liver to the diaphragm
and anterior abdominal wall. Contains the round ligament of liver (Teres) +
Paraumbilical vein, which connects portal vein with subcutaneous veins in umbilical
region.
3. Teres ligament of liver: (Round ligament) lies in the free margin of Falciform ligament
and ascends from umbilicus to the inferior (visceral) surface of liver, lying in a fissure
that forms the L. boundary of the quadrate lobe of the liver. Remnant of L. umbilical vein
(The R. umbilical: obliterated during embryonic period).
4. Coronary ligament of the liver: peritoneal reflection from diaphragmatic surface of liver
onto diaphragm and encloses a triangular area of the R. lobe Bare area of liver. Has a
R. and L. triangular ligaments (as extensions on both sides of liver)
5. Ligamentum Venosum: fibrous remnant of ductus venosus. Lays in a fissure on the
inferior surface of liver boundary for the caudate lobe of liver.
6. Hepatoduodenal ligament (see above)

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7. Hepatogastric ligament (see above)

8. Gastrolineal (Gastrosplenic) ligament (see above)
9. Lienorenal (Splenorenal) (Phrenicosplenic) ligament (see above)
10. Gastrophrenic ligament (see above)
11. Gastrocolic ligament (see above)
12. Root of the mesentery, mesentery: contains the Superior mesenteric vessels, lymph
nodes and nerve branches

Peritoneal folds: peritoneal reflections with free edges

1. Umbilical folds: discussed previously.

2. Rectouterine fold: from cervix of uterus, along side of rectum to posterior pelvic wall,
forming Rectouterine pouch of Douglas (in females)
3. Ileocecal fold: terminal ileum to cecum.

***Note:
We have to distinguish the Paracolic gutters from the peritoneal gutters or recesses:

The Paracolic gutters: are spaces between the ascending / descending colons and the lateral
abdominal wall, we have 2:
- Right Paracolic gutter
- Left Paracolic gutter

The paramesenteric (mesentero-colic) gutters or recesses: are two spaces (or recesses) in
the abdominal cavity between the colon and the root of the mesentery. We have 2 paramesenteric
gutters;
- Right paramesenteric gutter, defined by:
o Ascending colon or cecum laterally
o Transverse colon superiorly
o Root of mesentery medially

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- Left paramesenteric gutter, defined by:

o Root of mesentery medially
o Descending colon laterally

** These gutters are clinically important because they allow a passage for infectious fluids from
different compartments of the abdomen. For example:
Fluid from an infected appendix can track up the right Paracolic gutter to the Hepatorenal recess.

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Body surface divisions and important lines:

- Monro-Richter line: a line passing from the umbilicus to the anterior superior iliac spine
(ASIS)
- McBurney point: Located on the lateral 1/3 of the Monro-Richter line, marks the
approximate location of the base of appendix for appendectomy incision and a sign of acute
appendicitis if tenderness occurs in that area
- Opposite McBurney point: same location of McBurney's point, but on the left lumbar region
(left side of the body). This point is used for puncture and drainage of the peritoneal cavity
- Monro point: in some sources, located on the interspinal line of Lanz, just going vertically
below the McBurney's point. Also used for approximation of the location of appendix in
appendectomy operation

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It can be divided into simpler 4 quadrants by 2 lines:

- Median plane line
- Transumbilical line (horizontal line through the umbilicus)

After intersection, both lines will give: RUQ, RLQ, LUQ, LLQ.

Right upper quadrant (RUQ): Left upper quadrant (LUQ):

Liver, R lobe (RH) Liver: L lobe
Gall bladder (RH) can palpate it at X Spleen
Stomach: pylorus (E) Stomach
Duodenum: parts 1-3 (E) Jejunum + proximal part of ileum
Pancreas: head (E) Pancreas (body + tail)
R suprarenal gland L kidney
R kidney L suprarenal gland
R colic (hepatic) flexure (RH) L colic (splenic) flexure
Ascending colon: superior part (RL) Transverse colon (L. half)
Transverse colon, R half Descending colon (superior part)

Right lower quadrant (RLQ): Left lower quadrant (LLQ):

Cecum Sigmoid colon
Vermiform appendix Descending colon (inferior part)
Most of ileum L. ovary
Ascending colon (inferior part) L. uterine tube
R. ovary L. uerter (abdominal part)
R. uterine tube L. spermatic cord
R. ureter (abdominal part) Uterus (if enlarged)
R. spermatic cord Urinary bladder (if full)
Uterus (if enlarged)
Urinary bladder (if full)

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Internal surface of the anterolateral abdominal wall, preperitoneal space:

The Preperitoneal space is located between the anterior parietal peritoneum and the
trasversalis fascia. Structures situated here cause 5 folds on the parietal peritoneum:
4. Median umbilical fold (unpaired): extends from the apex of urinary bladder to
the umbilicus and covers the median umbilical ligament, remnant of the urachus,
which joined the apex of fetal bladder to the umbilicus
5. Medial umbilical folds (paired): lateral to median umbilical fold, cover the
medial umbilical ligaments, formed by the occluded parts of umbilical arteries
(remnants)
6. Lateral umbilical folds (paired): lateral to medial umbilical folds, cover the
inferior epigastric vessels can cause severe bleeding in case of cut

FSV: Supravesical fossa

FIM: Medial inguinal fossa (at the level of the superficial inguinal ring),
contains the Hasselbach trigone (inguinal triangle):
The triangular area in the lower abdominal wall bounded inferiorly by the
inguinal ligament, the border of the rectus abdominis medially and the
inferior epigastric vessels (lateral umbilical fold) laterally. It is the site of
direct inguinal hernia.
FIL: Lateral inguinal fossa, lateral to lateral umbilical folds, including the
deep inguinal rings, potential site for indirect hernia

** Going
downwards, the
preperitoneal
space gets wider:
supravesical and
prostatic spaces
(and prevesical
space of Retzius).
Via the subarcuate
hiatus the deep
dorsal vein of

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penis enters the vesical venous plexus.

** The supraumbilical part of the internal surface has a saggitaly oriented peritoneal
reflection: the falciform ligament extending to the liver, and enclosing the round ligament
of liver (Teres ligament) + Paraumbilical vessels in its free edge.

Hernia:

A condition in which a portion of the intestines protrudes through a weak spot of the
body

1. Abdominal hernias:
a. Umbilical hernia: common in newborns, through the weak umbilical ring.
It can be acquired in pregnant women or obese people
b. Epigastric hernia: through the Linea alba in the epigastric region, between
the xiphoid process and umbilicus in midline
c. Spigelian hernia: along the semilunar lines, in obese people > 40 years
d. Incusional hernia: through a surgical incision
e. Lumbocostal hernia: between diaphragms lumbar and costal parts, lateral
to the Arcuate ligament becomes the Bochdalek foramen hernia
(pleuroperitoneal)
f. Lumbar hernia:
1. Grynfelt triangle: bordered by the 12th rib + Serratus posterior
inferior muscle + internal oblique muscle + Quadratus lumborum
2. Petit triangle: bordered by the Latissimus Dorsi, external oblique
muscles and Iliac crest (Check dorsal regions, back)
g. Femoral hernia: through femoral canal, discussed in the Subinguinal
hiatus
h. Hiatal hernia: pars of the stomach passing into the mediastinum through
the esophageal hiatus of the diaphragm. Can be paraesophageal (rolling)
or sliding

2. Inguinal hernias:
a. Indirect inguinal hernia: a congenital condition, associated with the
presence of patent processus vaginalis, and covered by peritoneum and
coverings of the spermatic cord. The hernia passes through the Deep
inguinal ring, inguinal canal and the superficial ring descends into the
scrotum (if entire stalk of the processus vaginalis persists)
Hernia lays lateral to the inferior epigastric vessels (lateral umbilical fold).

b. Direct inguinal hernia: an acquired condition, associated with weakness

in the abdominal wall (posterior wall of the inguinal canal, lateral to the
Falx inguinalis, and has a sac that is formed by the peritoneum and
sometimes the trasversalis fascia)
Lays medial to the lateral umbilical fold, in the medial inguinal fossa,
through the Hasselbach (inguinal) triangle, and doesn't descend to the
scrotum, but can protrude forward to the superficial inguinal ring

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Fascia & triangles of the

neck, Nuchal region

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Fascia of the neck

A. Cervical subcutaneous tissue (Superficial cervical fascia) & Platysma:
A layer of fatty connective tissue that lies between the dermis of the skin and the investing
layer of the deep cervical fascia. It's thin anteriorly & contains cutaneous nerves, blood and
lymph vessels, superficial lymph nodes and adipose tissue.

The Platysma muscle is found anterio-laterally, it's broad and thin sheet facial muscle.
Origin: the subcutaneous layer and fascia covering the Pectoralis major and deltoid at
level of first or second rib
Insertion: on the lower border of mandible, Risorius and Platysma of opposite side
Action: depress the lower lip, forms ridges in skin of neck and upper chest when jaws
are “clenched”, denoting stress, anger. (used for stretching the anteriolateral neck for
shaving in men)
Nerve supply: cervical branch of facial n. (CN-VII), as the superficial cervical ansa,
anastomosing with the sensory transverse cervical nerves coming from the cervical
plexus
Features: deep to the Platysma, we find the external jugular vein descending from the
angle of mandible until the middle of clavicle

B. Deep cervical fascia:

Consists of 3 fascial layers or sheaths: Investing (superficial lamina), pretracheal (middle
lamina) & prevertebral (deep lamina), that support the neck viscera, muscles, vessels & deep
lymph nodes. They form natural separation between tissues in surgery and limit spread of
abscesses resulting from infections. It allows also slipperiness for structures in the neck to
move smoothly without difficulty during head movements and swallowing.

1. Investing layer of deep cervical fascia (superficial lamina):

Surrounds the entire neck deep to the skin and encloses the trapezius &
sternocleidomastoid muscles.
Superiorly, the investing layer of deep cervical fascia is connected to:
Superior Nuchal line of occipital bone
Mastoid process of temporal bone
Zygomatic arches
Inferior border of mandible
Hyoid bone
Spinous process of the cervical vertebrae

It encloses the submandibular gland, forms the fibrous capsule of the parotid gland, and
thickened to form the stylomandibular ligament

Posteriorly is continuous with the periosteum of C7 spinous process and with the Nuchal
ligament.

The inferior attachment of the investing layer is:

Manubrium
Clavicles
Acromions
Spines of scapulae

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At the attachment on the manubrium, the investing layer divides into anterior & posterior
layers to form the supra-sternal space, which contains:
anterior jugular veins
jugular venous arch
fat
deep lymph nodes

2. Pretracheal layer of deep cervical fascia (middle lamina):

Thin layer, limited to the anterior of the neck, extending inferiorly from the hyoid
bone into the thorax, blending with the fibrous pericardium, it has:
Muscular part: enclosing the infrahyoidal muscles (including the Omohyoid
laterally)
Visceral part: enclosing the thyroid gland, trachea & esophagus, continuous
posteriorly & superiorly with the buccopharyngeal fascia of the pharynx

Laterally the pretracheal fascia blends with the carotid sheaths.

In the region of hyoid bone, it thickens to form the trochlea through which
intermediate tendon of digastric muscle passes

3. Prevertebral layer of deep cervical fascia (deep lamina):

Forms a tubular sheath for the vertebral column and muscles associated with it
(longus capitis, longus colli anteriorly) (scalene laterally) (deep cervical muscles
posteriorly)
Superiorly it's fixed to the cranial base
Inferiorly it blends with the endothoracic fascia peripherally, and the anterior
longitudinal ligament centrally at Th-3 vertebra level
Laterally it extends as the axillary sheath, enclosing the axillary vessels & brachial
plexus

Carotid sheath: tubular fascial investment that extends from the cranial base to the
root of the neck. Anteriorly it blends with the investing & pretracheal layers of fascia
and posteriorly with the prevertebral layer. It contains:
Common & internal carotid arteries
Internal jugular vein
Vagus nerve (CN-X)
Deep cervical nodes
Carotid sinus nerve of Hering (branch of glossopharyngeal nerve CN-IX)
Sympathetic nerve fibers (carotid periarterial plexuses)

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Peripharyngeal space
The space, filled with loose areolar tissue, around the pharynx; it is divided into two portions,
Parapharyngeal space and retrovisceral space.

1) Parapharyngeal space (Lateral pharyngeal space, Pharyngomaxillary space) (PPS):

The PPS is a potential space in the shape of an inverted pyramid with its base at the skull
base and its apex at the greater horn of the hyoid bone. Various fascial layers within the
PPS result in further compartmentalization of this complex anatomic region.

The superior limit of the PPS is the base of skull, namely the sphenoid and temporal
bones. It includes in this area the jugular and hypoglossal foramina and the foramen
lacerum (through which the internal carotid artery passes)

The medial wall of the PPS is formed superiorly by the pharyngobasilar fascia & the
superior pharyngeal constrictor (Naso- & Oropharynx)

The posterior-lateral limit of the PPS consists of the prevertebral fascia & paravertebral
musculature

The posterior-medial limit of the PPS is the retrovisceral space & deep lobe of the
parotid gland

The anterior limit is formed by the Pterygomandibular raphe

The inferior limit of the PPS is represented by the junction of the posterior belly of the
digastric muscle and the greater horn of the hyoid bone.

The lateral wall of the PPS is formed by, from anterior to posterior, the medial Pterygoid
fascia (Covering the masticatory space, containing the masticatory muscles), ramus of the
mandible, Retromandibular portion of the deep lobe of the parotid, and below the level of
mandible, the posterior belly of the digastric muscle.

Using the tensor veli-styloid fascia (runs between the tensor veli palatini muscle, styloid
process and styloid musculature) as separating layer the parapharyngeal space can be
subdivided into two compartments:
Prestyloid compartment: found anterolaterally
Poststyloid compartment: found posteriomedially (including the carotid
sheath & space)

Contents of this space: in its anterior part the following muscles: Stylopharyngeus,
Styloglossus, and Stylohyoid. In its posterior part we can find the Glossopharyngeal,
Vagus, accessory, hypoglossal nerves, the cervical sympathetic trunk, the internal
Carotid artery, the Internal Jugular vein, and of course, some lymph nodes.

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2) The Retrovisceral space:

The retrovisceral space is divided into the retropharyngeal space and the danger
space by the alar fascia.
The alar fascia is considered in most of the sources as part of the prevertebral fascia, as a
thin layer attaching to the midline of the buccopharyngeal fascia from the cranium to the
level of C7 vertebra, from this attachment it extends laterally and terminate in the carotid
sheath.

** The retrovisceral space is of particular clinical importance because it is a main route

by which oropharyngeal infections can spread into the mediastinum.

a) The retropharyngeal space:

A virtual space behind the pharynx, bordered by:
Anteriorly: the pretracheal fascia (buccopharyngeal fascia)
Posteriorly: the alar fascia
Superiorly: base of the skull
Laterally: the carotid sheath

It extends from the base of skull superiorly until the level of the Th-4 vertebra level,
where the pretracheal & alar fasciae fuse together (Separated from the mediastinum)

It is divided by the midline attachment of the alar fascia into the buccopharyngeal
fascia to right & left spaces, making infections occurring in this space look unilateral
The retropharyngeal space contains:
Adipose tissue
The retropharyngeal lymph nodes: three groups of lymph nodes, one median
and two lateral, they receive lymph from the nasopharynx, the auditory tube,
and the atlanto-occipital and atlantoaxial joints

b) The danger space:

A virtual space found anterior to the prevertebral fascia (covering the cervical spine
& musculature) and posterior to the alar fascia, so it's behind the retropharyngeal
space.
This space is limited superiorly by the base of the skull, but communicates freely with
the posterior mediastinum inferiorly, reaching the level of the diaphragm, allowing a
carnio-caudal spread of infection (hence the name), and what makes it more
dangerous is that this space has no midline raphe (As in the retropharyngeal space),
so the infections can easily spread to either side.

** Clinical importance of the retrovisceral space, example:

This is most commonly seen in children. The infection begins in the lymphatic tissue of
Waldeyers ring and spreads to the retropharyngeal lymph nodes, causing adenitis. These
nodes may become suppurative and eventually cause retropharyngeal cellulites or
a retropharyngeal abscess.
Pus from this abscess can either cross the alar fascia reaching the danger space, and
from there to the posterior mediastinum infecting the structures found there, or it can
reach laterally to the prestyloid compartment of the parapharyngeal space and damage
the cranial nerves (IX, X, XI, XII) located there.

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* Radiographically, pathology within this danger space cannot be distinguished

from retropharyngeal space pathology.
** Some sources indicate that the retrovisceral space is the same as the retropharyngeal
space

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Cervical Regions/Triangles and their contents:

A) Sternocleidomastoidal region:
The area over the SCM muscle, we can find there:
Superior part of external jugular vein
Transverse cervical & greater auricular nerves

Lesser supraclavicular fossa: a space between the two heads of origin of the
sternocleidomastoid muscle. It contains:
o Inferior part of the internal jugular vein

B) Posterior cervical region (Nuchal region):

The back of neck, including trapezius muscles & the suboccipital region laying deep in
the superior part of this region (check dorsal regions for description of this region)

C) Lateral cervical region (posterior triangle of neck):

We find here:
Occipital (Omotrapezius) triangle: a triangle of the neck bounded by the
trapezius, the sternocleidomastoid, and the omohyoid muscles. It contains:
o external jugular vein
o transverse cervical artery
o spinal accessory nerve
o trunks of brachial nerve plexus
o posterior branches of cervical nerve plexus

Omoclavicular (Supraclavicular, Subclavian) triangle: the triangle bounded

by the clavicle, the omohyoid muscle, and the sternocleidomastoid muscle. It
contains:
o Subclavian artery & vein (vein not always)
o Suprascapular artery
o Suprascapular lymph nodes (on the left side, its called Signal or
Virchow lymph node, that can have metastasis of gastric cc.)

** The term greater supraclavicular fossa was formerly considered a

synonym for the omoclavicular triangle, today the Terminologica
Anatomica still reserves this term for the surface feature that overlies the
omoclavicular triangle: a depressed area above the middle of the clavicle,
lateral to the sternocleidomastoid.

** The Scalenotracheal fossa:

The deep part of the supraclavicular region, between the scalenus anterior
muscle and the trachea. Inside, there are longitudinal and transverse
structures:
The longitudinal structures are:
o Structures of the carotid sheath and those parallel to it
o Middle ganglion of the cervical sympathetic trunk, from the
middle cervical ganglion, fibers surrounding the subclavian
artery are called the ansa subclavia

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The transverse structures are branches of the thoracic part the

subclavian artery passing through the fossa:
o Thyrocervical trunk and its branches (mainly the inferior
thyroid artery)
o The inferior thyroid artery goes to the thyroid gland and
crosses a nerve in the scalenotracheal fossa; the inferior
laryngeal nerve (or recurrent laryngeal nerve)
o The vertebral artery, which ascends through the transverse
foramen of the cervical vertebrae
o The internal thoracic artery, descending to run parallel to
sternum on the interior of the thoracic cavity

** The recurrent laryngeal nerve comes from the thoracic cavity. The left
recurrent laryngeal nerve hooks around the aortic arch and the right nerve goes
around the right subclavian artery because both develop from the 4th branchial
arteries.

** From a surgical point of view, this crossing is very important because if a

surgeon operates on the thyroid gland, he has to ligate first the superior and
inferior thyroid arteries to cut the gland. If the surgeon cuts this nerve, the
patient will have a big problem, because the inferior laryngeal nerve innervates
all the intrinsic muscles of the larynx (except the Cricothyroid), and the voice of
the patient will be affected (Husky voice)

D) Anterior cervical region (anterior triangle of neck):

The area of the neck bounded by the mandible, the anterior border of the
sternocleidomastoid muscle, and the anterior midline of the neck, it is subdivided into:
Submandibular (digastric triangle): the triangle of the neck bounded by the
mandible and the two bellies of the digastric muscle, it contains:
o Submandibular gland
o Submandibular lymph nodes
o Mylohyoidal nerve
o Part of facial artery & vein

Submental triangle: a triangle bounded by the anterior belly of the digastric

muscles, the hyoid bone, and the midline; the mylohyoid muscle forms its
floor. It contains:
o Submental lymph nodes
o Small veins, that unite to form the anterior jugular veins

Carotid triangle (Gerdy hyoid fossa): a space bounded by the superior belly
of the omohyoid muscle, anterior border of the sternocleidomastoid, and
posterior belly of the digastric. It contains:
o Carotid sheath with its contents
o Hypoglossal nerve
o Superior root of ansa cervicalis
o Spinal accessory nerve
o Thyroid gland
o Larynx
o Pharynx
o Deep cervical lymph nodes

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Muscular (omotracheal) triangle: the triangle bounded by the

sternocleidomastoid muscle, the superior belly of the omohyoid muscle, and
the anterior midline of the neck, it contains:
o Infrahyoidal muscles (Sternothyroid, Sternohyoid, thyrohyoid)
o Thyroid gland

** The 2 muscular trigons are called middle cervical region

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The Nuchal Region:

Borders: Superior: External Occipital Protuberance

Lateral: A line along the side of Mastoid process
Inferior: Vertebral Prominence (7th Cervical)
Medial: a vertical line From the External Occipital Protuberance to the
Vertebral Prominence

Skin Innervation:
Lesser Occipital nerve (C2/C3, Cervical plexus)
Greater Occipital nerve (Dorsal branch of C2)
Tertiary Occipital nerve (Dorsal branch of C3)

Beneath the skin, the superficial nuchal fascia, covers the trapezius medialy and laterally the
splenius capitis.
If you remove the fascia, you will see the trapezius. Beneath the trapezius, lies the splenius
capitis muscle, a V-shaped muscle originating from the spinous processes of the lower
cervical and upper thoracic vertebrae and ascending to the superior nuchal line of the
occipital bone. The lateral part of the splenius capitis is called the splenius cervices because
lateral fibers do not ascend to the skull, but they terminate on the transverse processes of the
cervical vertebrae.

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Cutting the splenius capitis and cervicis, you will see the semispinalis capitis muscle, an
upsidedown V-shaped muscle (like the greek delta) originating from the transverse processes
of the upper thoracic and lower cervical vertebrae and inserting to the superior nuchal line,
medial to the splenius capitis. The semispinalis and splenius capitis make the rounded shape
to the back of the neck.
The great occipital nerve and the tertiary occipital nerve can be seen coming out from the
deep through these muscles, becoming superficial, and turning onto the head.
Together with the lesser occipital nerve, we have the occipital artery (a little deeper).
Deep to the semispinalis capitis, the deep nuchal fascia covers the suboccipital triangle and
the semispinalis cervicis muscle

The Suboccipital Triangle:

Borders:
Lateral: Obliquus capitis superior (origin, transverse process of atlas; insertion,
lateral third of inferior Nuchal line)
Infeior: Obliquus capitis inferior (origin, spinous process of axis; insertion,
transverse process of the atlas, note that despite its name, it has to attachment to
the skull)
Superior:
o Rectus Capitis Posterior Major (origin, spinous process of axis; insertion,
middle of inferior Nuchal line of occipital bone)
o Rectus Capitis Posterior Minor (medial to Major) (origin, from posterior
tubercle of atlas; insertion, medial third of inferior Nuchal line of
occipital bone)
Roof: Deep Nuchal Fascia
Flooer: Posterior Atlatnococcupital membrane

Contents:
Vertebral Artery: Located on the posterior arch of Atlas (can be palpated) in the
vertebral suclus. On the atlas, it runs a little lateral, and then turns medially. after,
it pierces through the posterior atlantooccipital membrane and enters the skull to
supply the brain
Suboccipital nerve: dorsal ramus of C1, passing through the suboccipital triangle
and sending branches to the Rectus capitis posterior major and minor, Obliquus
capitis superior and inferior, Rectus capitis Lateralis, and semispinalis capitis. its
generally considered to have only motor fibers, but the suboccipital nerve
receives sensory fibers for proprioception via a communicating branch from the
second cervical spinal nerve

At the lateral border of the region, you can see the Sternocleidomastoid muscle (arising from
the Manubrium of Sternum and medial third of the clavicle and inserting to the mastoid
process of the temporal bone and the occipital bone)

** The important thing about this region is to know the layers, so let's summarize up the
layers from most superficially to the deepest:
1) Skin
2) Subcutaneous fat
3) Superficial nuchal fascia
4) Trapezius muscle (Descending fibers, inverted V-shape)

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5) Splenius Capitis muscle (V-shaped)

6) Semispinalis Capitis muscle (inverted V-Shape, or vertical | | )
7) Deep Nuchal fascia
8) Suboccipital Triangle
9) Posterior Atlantooccipital membrane
10) Semi Spinalis Cervices muscle

* Drawing By Dr. Hanics:

1- Atlas (Posterior Tubercle)

2- Axis (Spinous Process)
3- Atlas (Transverse Process)
4- Obliquus capitis inf. M.
5- Obliquus capitis sup. M.
6- Rectus capitis post. Major m.
7- Rectus capitis post minor m.
8- Trapezius m.
9- Sternocleidomastoid m.
10- Splenius capitis m.

The External Carotid Artery

The external carotid artery begins the upper border of the thyroid cartilage, and, taking a slightly
curved course, passes upward and forward, and then inclines backward to the space behind the
neck of the mandible, where it divides into the superficial temporal and maxillary arteries. It
rapidly diminishes in size in its course up the neck. In the child, it is somewhat smaller than the
internal carotid; but in the adult, the two vessels are of nearly equal size. At its origin, this artery
is more superficial, and placed nearer the middle line than the internal carotid, and is contained
within the carotid triangle.

Relations:
The external carotid artery is covered by the skin, superficial fascia, Platysma, deep
fascia, and anterior margin of the Sternocleidomastoid. It is crossed by the hypoglossal
nerve, by the lingual, common facial, and superior thyroid veins; and by the Digastric and
Stylohyoid.
Higher up it passes deeply into the substance of the parotid gland, where it lies deep to
the facial nerve and the junction of the temporal and internal maxillary veins. Medial to it
are the hyoid bone, the wall of the pharynx, the superior laryngeal nerve, and a portion of
the parotid gland. Lateral to it, in the lower part of its course, is the internal carotid
artery. Posterior to it, near its origin, is the superior laryngeal nerve; and higher up, it is
separated from the internal carotid by the Styloglossus and Stylopharyngeus, the
glossopharyngeal nerve, the pharyngeal branch of the Vagus, and part of the parotid
gland.

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Branches: The branches of the external carotid artery may be divided into four sets:

1. Anterior: Superior Thyroid, Lingual, Facial artery

2. Posterior: Occipital, Posterior Auricular, Sternocleidomastoidal (not always)
3. Ascending: Ascending Pharyngeal
4. Terminal: Superficial Temporal, Maxillary
A) Anterior

1. Superior thyroid artery: arises from the external carotid artery just below the
level of the greater horn of the hyoid bone and ends in the thyroid gland. Besides
the arteries distributed to the muscles and to the thyroid gland, the branches of the
superior thyroid artery are: Infrahyoid, Superior Laryngeal,
Sternocleidomastoidal and Cricothyroid.

2. Lingual artery: arises from the external carotid between the superior thyroid
and facial artery; it first runs obliquely upward and medial toward to the greater
horn of the hyoid bone; it then curves downward and forward, forming a loop
which is crossed by the hypoglossal nerve, (Pirigoff trigone) and passing beneath
the Digastric and Stylohyoid it runs horizontally forward, beneath the Hyoglossus,
(Beclard trigone) and finally, ascending almost perpendicularly to the tongue,
turns forward on its lower surface as far as the tip giving the Suprahyoidal, dorsal
lingual branches and sublingual artery.

3. Facial artery: arises in the carotid triangle a little above the lingual artery and,
sheltered by the ramus of the mandible, passes obliquely up beneath the Digastric
and Stylohyoid, over which it arches to enter a groove on the posterior surface of
the Submandibular gland. It then curves upward over the body of the mandible at
the antero-inferior angle of the Messeter; passes forward and upward across the
cheek to the angle of the mouth, then ascends along the side of the nose, and ends
at the medial commissure of the eye, under the name of the angular artery. It
gives the ascending palatine, tonsillar, glandular, submental, inferior labial,
superior labial, messeteric, buccal and lateral nasal branches before terminating as
the angular artery.

** Sometimes the lingual and facial arteries both arise in a common trunk called
the Linguofacial trunk.

B) Posterior

1. Occipital artery: arises from the posterior part of the external carotid, opposite
the facial artery, near the lower margin of the posterior belly of the Digastric, and
ends in the posterior part of the scalp giving auricular, mastoidal, occipital and
meningeal branches.

2. Posterior auricular artery: it's small and arises from above the Digastric and
Stylohyoid, opposite the apex of the styloid process. It ascends, under the parotid
gland, on the styloid process of the temporal bone, to the groove between the
cartilage of the ear and the mastoid process, and then it divides into its auricular
and occipital branches.

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C) Ascending

Ascending pharyngeal artery: the smallest branch of the external carotid is a

long, deeply seated in the neck, beneath the other branches of the external carotid
and under the Stylopharyngeus. It arises from the back part of the external
carotid, and ascends vertically between the internal carotid and the side of the
pharynx, to the under surface of the base of the skull, lying on the Longus capitis.

D) Terminal

1. Superficial temporal artery: the smaller of the two terminal branches of the
external carotid, appears, from its direction, to be the continuation of that vessel.
It begins in the substance of the parotid gland, behind the neck of the mandible,
and crosses over the posterior root of the zygomatic process of the temporal bone;
about 5 cm. above this process it divides into two branches, a frontal and a
parietal.

2. Maxillary artery: the larger of the two terminal branches of the external
carotid, arises behind the neck of the mandible, and is at first imbedded in the
substance of the parotid gland; it passes forward between the ramus of the
mandible and the sphenomandibular ligament, and then runs to the
pterygopalatine fossa. It supplies the deep structures of the face, see details later

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The Maxillary artery (Internal maxillary artery)

This vessel is the larger of the 2 terminal branches of the external carotid artery (other branch
being the superficial temporal a.).
It arises posterior to the neck of the condylar process of the mandible, within the parotid gland,
and passes anteriorly deep to the neck, traversing the infratemporal fossa. It passes superficial to
the lateral Pterygoid muscle and then disappears in the infratemporal fossa.

The maxillary artery is divided into 3 parts in relation to the lateral Pterygoid muscle.

The 1st part passes deep to the neck of the mandible between the bone and
sphenomandibular ligament and runs anteriorly lateral to the inferior alveolar n. to reach
the border of the lateral Pterygoid.

The 2nd part angles anteromedial between the 2 heads of the lateral Pterygoid and anterior
and posterior divisions of the Mandibular nerve.

The 3rd part leaves the lateral Pterygoid to enter the pterygopalatine fossa where it
terminates as branches that accompany the branches of the maxillary division of the
trigeminal nerve.

A) Branches of the 1st part of maxillary artery:

1. Deep auricular: to the external acoustic meatus

2. Anterior tympanic: to the tympanic membrane

3. Middle meningeal:
The most important artery of the dura matter, it passes through the foramen
spinosum into the middle cranial fossa. During its extra-dural course it divides
into an anterior and posterior branch. This artery is usually surrounded near its
origin by 2 branches of a cutaneous nerve, the auricotemporal n. (branch of
Mandibular n. V3)

4. Accessory meningeal arteries: to the cranial cavity

5. Inferior alveolar:
Gives off the mylohyoid branch, before entering the Mandibular canal along with
the inferior alveolar n.
This artery supplies the teeth, bone and soft tissues of the lower jaw. Finally as
the mental artery it traverses the mental foramen to run to the skin of the chin.

B) Branches of the 2nd part of maxillary artery: all are branches to the muscles of mastication,

1. Massetric
2. Deep anterior and posterior temporal arteries.
3. Pterygoid branches
4. Buccal: to the cheek and buccal mucous membrane.

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C) Branches of the 3rd part of the maxillary artery: these branches arise just before it enters the
pterygopalatine fossa,

1. Superior posterior alveolar: enters the maxilla at the maxillary tuberosity, and
supplies the molar teeth and gums. It forms an anastomosis with the infraorbital branch

2. Infraorbital: which passes through the inferior orbital fissure to the orbit and leaves it
through the infraorbital canal and foramen, on its way the infraorbital a. gives off the
anterior superior and middle superior alveolar arteries which supply the incisor, canine
and premolar teeth and related gums.

3. Descending palatine: reaches the hard palate through the pterygopalatine canal. It
emerges from the greater palatine foramen, runs forward in groove on the medial side of
the alveolar border of the hard palate to the direction of incisive canal, where it
anastomosis with the nasopalatine artery.
Branches are distributed to the gums, palatine glands and the mucous membrane of the
roof of the mouth. In the pterygopalatine canal it gives off twigs of branches that descend
in the lesser palatine canals to supply to soft palate and palatine tonsils, anastomosing
with the ascending palatine a.
**(some sources state the descending palatine a. branches into the great and lesser
palatine arteries, while other sources equate the descending palatine to the greater
palatine artery)

4. Artery of Pterygoid canal: runs in this canal to reach the upper pharynx and
Eustachian tube

5. Pharyngeal artery: runs through the Palatovaginal canal, on the undersurface of the
vaginal process of the sphenoid bone, which is a furrow that is converted into a canal by
the Sphenoidal process of the palatine bone; it transmits the pharyngeal branch of the
maxillary artery and the pharyngeal nerve from the pterygopalatine ganglion.

6. Sphenopalatine artery: enters the nasal cavity through the nasopalatine foramen, and
supplies the lateral, posterior and medial walls via the posterior lateral nasal arteries

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Facial artery (External maxillary artery):

An anterior branch of the external carotid artery that supplies structures in the face, The facial
artery arises in the carotid triangle from the external carotid artery a little above the lingual
artery and, sheltered by the ramus of the mandible, passes obliquely up beneath
the digastric and stylohyoid muscles, over which it arches to enter a groove on the posterior
surface of the submandibular gland.

It then curves upward over the body of the mandible at the antero-inferior angle of
the masseter; passes forward and upward across the cheek to the angle of the mouth, then
ascends along the side of the nose, and ends at the medial commissure of the eye, under the
name of the angular artery.

** This vessel, both in the neck and on the face, is remarkably tortuous: in the former situation,
to accommodate itself to the movements of the pharynx in deglutition; and in the latter, to the
movements of the mandible, lips, and cheeks.

Branches:

A. Cervical branches:

1. Ascending palatine artery: arises close to the origin of facial, and passes between the
Styloglossus & Stylopharyngeus to the side of the pharynx up the base of skull between
the superior constrictor of pharynx & medial Pterygoid muscle. It supplies:
a. Lateral walls of pharynx
b. Palatine tonsils
c. Auditory tubes
d. Soft palate

2. Tonsillar branch: primary blood supply to palatine tonsil, with extensive anastomoses
with other tonsillar arteries

3. Glandular branches: branches of facial artery to the submandibular gland

4. Submental artery: largest cervical branch that runs forward upon the mylohyoid, just
below the mandible, and beneath the digastric muscle. It supplies the mylohyoid
muscle, submandibular and sublingual glands, and structures of lower lip &
anastomoses with the inferior labial, mental branch of inferior dental (alveolar) and
sublingual artery.

B. Facial branches:

1. Inferior labial artery: arises near the angle of mouth, penetrates the Orbicularis Oris
muscle and runs in a tortuous course along the edge of the lower lip between this
muscle and the mucous membrane. It supplies the structures of the lower lip (labial
glands, muscle, and mucous membrane)

2. Masseteric & Buccal branches: branches to the muscles of cheek and masseter that
anastomose with the same branches of maxillary artery.

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3. Superior labial artery: also arises near the angle of mouth, penetrates the Orbicularis
Oris muscle and runs in a tortuous course along the edge of the upper lip between this
muscle and the mucous membrane and supplies:
a. Structures of the upper lip (labial glands, muscle and mucous membrane)
b. The anterior, lower part of nasal septum by a septal branch
c. Lateral side of the external nose by an alar branch

4. Lateral nasal branch: branch of facial artery to the side of the nose (ala and dorsum);
anastomoses with its contralateral partner, as well as the septal and alar branches of the
superior labial, the dorsal nasal branch of the ophthalmic, and the infraorbital branch of
the maxillary artery

5. Angular artery: a terminal branch of the facial artery that ascends to the medial angle
(commissure) of the orbit accompanied by the angular vein. It supplies the muscles and
skin of side of nose, and anastomosis with:
a. Lateral nasal branches
b. Infraorbital artery
c. Dorsal artery of nose (from the ophthalmic artery), thereby providing an
external-internal carotid arterial anastomosis

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