HUMAN ANATOMY

PART I

THORAX

BY

Jerzy Gielecki M.D, Ph.D

&

Anna Żurada M.D, Ph.D

Olsztyn 2019
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Lab. session 1

I. THORAX ........................................................................................ 4
1.1. THORACIC CAGE ........................................................................... 4
1.2. SURFACE LANDMARKS OF THE THORACIC WALL ................................ 6
1.3. MUSCULATURE OF THE THORAX ..................................................... 7
1.4. FASCIA OF THE THORACIC WALL ................................................... 12
II. NEUROVASCULAR BUNDLE OF THE THORACIC WALL ........ 13
2.1. ARTERIES OF THE THORACIC WALL ............................................... 13
2.2. VEINS OF THE THORACIC WALL ..................................................... 17
2.3. NERVES OF THE THORACIC WALL - INTERCOSTAL NERVES ............... 19
III. DIAPHRAGM................................................................................ 21
3.1. STRUCTURE OF THE DIAPHRAGM .................................................. 21
3.2. ARTERIAL SUPPLY OF THE DIAPHRAGM .......................................... 26
3.3. VENOUS DRAINAGE OF THE DIAPHRAGM ........................................ 26
3.4. LYMPHATIC DRAINAGE OF THE DIAPHRAGM .................................... 26
3.5. NERVE SUPPLY OF THE DIAPHRAGM .............................................. 26
IV. AXILLA ........................................................................................ 27
1.1. WALLS OF THE AXILLA ................................................................. 27
1.2. CONTENTS OF THE AXILLA ........................................................... 28
V. AXILLARY ARTERY .............................................................................. 29
2.1. RELATIONS OF THE AXILLARY ARTERY ........................................... 29
2.2. BRANCHES OF THE AXILLARY ARTERY ........................................... 30
VI. Axillary vein
………………………………………………………….3031
VII. Axillary limph nodes ………………………….……………………30
VIII. Breast ………………………….………………………..….…30
IX. TRACHEA .................................................................................... 33

X. BRONCHI ..................................................................................... 34
2.1. LOCALISATION OF THE BRONCHI ................................................... 34
2.2. THE RIGHT MAIN BRONCHUS ........................................................ 35
2.3. THE LEFT MAIN BRONCHUS .......................................................... 35
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2.4. STRUCTURE AND DIVISION OF TRACHEA AND BRONCHI .................... 36

XI. THE BRONCHOPULMONARY SEGMENTS ............................... 38
1. THE RIGHT BRONCHOPULMONARY SEGMENTS ................................ 38
2. THE LEFT BRONCHOPULMONARY SEGMENTS .................................. 38
XII. THE PLEURA.............................................................................. 39
1. STRUCTURE AND DIVISION OF THE PLEURA .................................... 39
2. THE PARIETAL PLEURA ................................................................ 40
3. THE VISCERAL PLEURA ................................................................ 40
4. THE PLEURAL SAC AND RECESSES ................................................ 41
5. LINES OF PLEURAL REFLECTION ................................................... 43
6. NERVE SUPPLY OF THE PLEURA.................................................... 44
XIII. THE LUNGS ............................................................................... 45
1. STRUCTURE AND DIVISION OF THE LUNGS ...................................... 45
2. THE HILUM OF THE LUNG ............................................................. 46
3. LOBES OF THE LUNG ................................................................... 48
4. NERVE SUPPLY OF THE LUNG ....................................................... 50
5. BLOOD SUPPLY OF THE LUNG ....................................................... 51
6. VENOUS DRAINAGE OF THE LUNG ................................................. 51
7. LYMPHATIC DRAINAGE OF THE LUNG ............................................. 52

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1. THORAX

The thorax is the upper part of the trunk located between the abdomen and the neck.

Thoracic cage
The following bony and cartilaginous elements form the thoracic cage (Fig.1-1):
 thoracic vertebrae
 ribs and costal cartilages
 sternum
The walls of the thoracic cage protect organs of two spaces:
 thoracic cavity (above diaphragm)
 abdominal cavity (beneath diaphragm).
The thoracic cage communicates with:
 neck by superior thoracic aperture (thoracic inlet)
 abdominal cavity by inferior thoracic aperture (thoracic outlet).

The thoracic cage contains some important organs such as:

the lungs, trachea, oesophagus and the heart with the great vessels.

The superior thoracic aperture is limited by:

 jugular notch (suprasternal notch) of the sternum
 first rib
 body of the first thoracic vertebra.
The inferior thoracic aperture is limited by:
 xiphoid process of the sternum
 eleventh and twelfth rib
 costal arch (costal margin) formed by costal cartliges of false ribs (from 7th to 10th )
 body of the twelfth thoracic vertebra

Posterior wall of the thoracic cage contains pulmonary grooves located on both sides of
the thoracic vertebrae.
In the front, lines of the costal arches form part of the inferior thoracic aperture.
Between them there is the infrasternal angle (subcostal angle) – Fig. 1-1. Usually it is about
90 o

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Fig. 1-1. Skeleton of the thorax

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Fig. 1-2. Vertical lines of thorax

1. 2. Surface landmarks of the thoracic wall

Vertical lines and lines of the ribs are used to describe the location of anatomical structures
within the thoracic cage. They are also used to describe the symptoms and results of a
physical examinations (Fig.1-2).
 anterior median line in the midsagittal plane
 posterior median line = spinous line
 parasternal line on the lateral margin of the sternum
 midclavicular line is the parasagittal plane through the midpoint of the clavicle
 mammilary line is the parasagittal plane through the nipple of the breast (male &
prepubertal female)
 midaxillary line is the coronal plane through the topmost point of the axilla
 scapular line is the parasagittal plane through the inferior angle of the scapula

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 paravertebral line is the parasagittal plane through the transverse processes of the
vertebrae.
The front of the chest is divided into pectoral regions. The pectoral regions are formed by:
 presternal region
 infraclavicular fossa
 pectoral region with:
 lateral pectoral region
 mammary region
 inframammary region
 axillary region with axillary fossa

The clavipectoral triangle is located in the pectoral region.

The clavipectoral triangle has three following boundaries:

Superior limit - Clavicle

Lateral limit – Deltoid
Medial limit - Pectoralis major

Fig. 1-3. The clavipectoral triangle

The clavipectoral triangle contains the following elements:

 thoraco-acromial artery
 cephalic vein
 thoraco-acromial vein
 deltopectoral lymph nodes
 infraclavicular fossa

1. 3. Musculature of the Thorax

Muscles of the thorax are divided into two groups:

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I. SUPERFICIAL MUSCLES of the anterior thoracic wall (the pectoral muscles).

The pectoral muscles: 4 in number (superficial muscles of the anterior thoracic wall) are
associated with movement of the upper limb.

1. Pectoralis major (musculus pectoralis maior)

Origin: (O:) medial 1/2 of the anterior surface of the clavicle, sternum, and costal cartilages
from 1 to 6, aponeurosis of the external oblique; there are 3 parts of this muscle:
 the clavicular part
 the sternocostal part
 the abdominal part
Insertion: (I:) greater tubercule of the humerus
Action: (A:) adduction, flexion and medial rotation of the arm (accessory muscle of
inspiration)

MNEMONIC: for pectoral muscles

A lady between two majors.
The pectoralis major attaches to the lateral lip of the bicipital groove, the teres major
attaches to the medial lip of the bicipital groove, and the latissimus dorsi attaches to the
floor of the bicipital groove.
The "lati" is between two "majors."

2. Pectoralis minor (musculus pectoralis minor)

O: outer surface of ribs 3-5 (between bone and cartilage)
I: coracoid process of the scapula
A: depression and protraction of the scapula (accessory muscle of respiration)

Fig. 1-4. The muscles of the thorax

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Nerve supply: (N:) both pectoral muscles - lateral and medial pectoral nerves; the short
branches of brachial plexus

3. Subclavius (musculus subclavius)

O: costal cartilage of the first rib
I: lower surface of clavicle
A: protection of the subclavian vessels
N: subclavian nerve (short branch of the superior trunk of brachial plexus)

4. Serratus anterior (musculus serratus anterior)

O: outer surface of ribs 1-8
I: medial border of scapula
A: fixation of scapula to the thoracic wall, protraction - accessory muscle of inspiration
N: long thoracic nerve (C5-C7) – short branch of brachial plexus

Fig. 1-5. The arterial supplay & innervation of the superficial muscles of the thorax

II. THE DEEP THORACIC MUSCLES (musculi thoracis profundi) are proper muscles of the
thorax.
Each of the 11 pairs of intercostal spaces contains the intercostal muscles (musculi
intercostales), which form three layers (Fig.1-3):

1. THE SUPERFICIAL - External intercostal muscles

The external intercostal muscles (musculi intercostales externi) extend from the tubercle of
the ribs posteriorly to the costochondral junctions anteriorly, where they terminate as an
external /anterior/ intercostal membrane - EIM (membrana intercostalis externa). They
arise from the lower border of the rib and end on the upper border of the rib below. The
intercostal fascia covers the outer surfaces of these muscles. Their fibres are directed
obliquely downward and forward.

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Direction of the fibers

Vertebra \\\\\\\\\\--EIM--Sternum--EIM--////////// Vertebra

MNEMONIC: for of the external oblique fiber direction

To remember the direction of the fibers of the external oblique, think of placing your hands
in your pockets, ie. down and in.

2. THE MIDDLE - Internal intercostal muscles

The internal intercostal muscles (musculi intercostales intermedii) occupy the intercostal
spaces from the costal cartilages anteriorly to the angles of the ribs, where they terminate
as an internal /posterior/ intercostal membrane - IIM (membrana intercostalis interna). The
intercostal fascia covers the inner surface of the internal intercostal muscles.

Their fibers run inferoposteriorly (in the direction opposite to the fibres of the external
intercostal muscles) from the costal groove to the superior border of the rib below.

Direction of the fibers

Vertebra--IIM--////////// Sternum \\\\\\\\\\--IIM--Vertebra

3. THE DEEPEST - Innermost intercostal muscles

The innermost intercostal muscles (musculi intercostales intimi) form the deepest layer of
the intercostal muscles and occupy the middle part of the intercostal spaces (from angle to
cartilage). The vasonervous fascicle (fasciculus vasonervosus) is situated between each pair
of the internal and the innermost intercostal muscles. It contains: Vein, Artery and Nerve
(VAN).

Function:
All intercostal muscles keep the intercostal spaces rigid and prevent them from being
bulged out during expiration and from being drawn in during inspiration.
The external intercostal muscles belong to the muscles of inspiration.
The internal intercostal muscles also partly (intercartilaginous part) belong to them.

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The rest of these muscles work as the muscles of expiration.

The function of the innermost intercostal muscles is not fully understood.
 The subcostal muscles (musculi subcostales) extend from the internal surface of
the angle of the rib to the internal surface of the rib below. They cross one or two
intercostal spaces. Their fibers run in the same direction as the fibers of the internal
intercostal muscles.
 The transverse thoracic muscle (musculus transversus thoracis) is attached to the
posterior surface of the inferior part of the body of the sternum and the posterior
surface of the costal cartilages (from the second to the sixth). Its fibers pass
superolaterally. The internal thoracic vessels (the internal thoracic artery and vein)
separate them from the costal cartilages and the internal intercostal muscles. The
transverse thoracic muscle is the muscle of expiration.

Fig. 1-6. Relations of fibers of the intercostal muscles and intercostal membrane

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1.4. Fascia of the thoracic wall

Fascia of the anterior thoracic wall can be divided into two layers:
superficial layer (lamina superficialis) covers the superficial muscles of the anterior
thoracic wall as pectoral fascia, which is attached: superiorly - to the clavicle, medially - to
the manubrium, inferiorly continuous as abdominal fascia and laterally - as axillary fascia
(forms floor of the axilla).
deep layer (lamina profunda) lies under the pectoral muscles.

A
Internal intercostal
membrane

B
Posterior primary branch
External
intercostal
Anterior primary branch muscle

Internal
Endothoracic fascia intercostal
& pleura muscle

Innermost intercostal muscle

Internal thoracic artery & veins C

(internal mammary artery& veins )

Sternocostalis muscle

Sternum
D
External intercostal
membrane
Fig. 1-7. Relations of the muscles and membranes of the intercostal space

The axillary fascia (fascia axillaris) continues posteriorly as posterior thoracic fascia and
distally as brachial fascia (fascia brachialis).
The clavicopectoral fascia (fascia clavicopectralis) is a strong fibrous sheet posterior to
the clavicular part of the pectoralis major. It covers the axillary vessels and nerves.

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The endothoracic fascia (fascia endothoracica) covers the internal surface of the ribs and
intercostal muscles, and corresponds to the transverse fascia (fascia transversalis) of the
abdominal wall.

II. Neurovascular Bundle of the Thoracic Wall

2.1. Arteries of the Thoracic Wall

The thoracic wall is supplied by many arteries, which arise from the thoracic aorta or their
branches.
The internal thoracic artery or internal mammary artery (arteria thoracia interna) is a
branch of the subclavian artery. It arises from the inferior surface of the first part of this
artery and descends on the posterior surface of the anterior thoracic wall, 1-2 cm lateral to
the sternum. The internal thoracic artery lies between:
the costal cartilages and the internal intercostal muscles anteriorly
the transverse thoracic muscles, the endothoracic fascia and the parietal pleura posteriorly.
The internal thoracic artery is crossed posteriorly by the phrenic nerve.
The internal thoracic artery gives off the following branches:
 anterior intercostal arteries between the first and sixth intercostal spaces
 mediastinal branches
 thymic branches
 pericardial branches
 pericardiacophrenic artery
 sternal branches
 perforating arteries which supply the pectoral muscles (with the medial mammary
branches)

The internal thoracic artery divides terminally at the level of the sixth intercostal space
into two branches (Fig: 1-5):
superior epigastric artery (arteria epigastrica superior) descends in the original direction
of the internal thoracic artery and passes through the diaphragm between the costal and
sternal attachments of the diaphragm into the anterior thoracic wall. Below the diaphragm
it supplies the muscles of the anterior abdominal wall and anastomoses with the inferior
epigastric artery (from the external iliac artery).
musculophrenic artery (arteria musculophrenica) is directed inferolaterally and descends
through the diaphragm at the level of the ninth rib and supplies the diaphragm. It gives off
branches to the lower part of the pericardium and the anterior intercostal arteries between
the sixth and ninth intercostal spaces.

The anterior intercostal arteries (arteriae intercostales anteriores) arise from the internal
thoracic artery and from the musculophrenic artery:
The superior anterior intercostal arteries (arteriae intercostales anteriores superiores)
arise from the internal thoracic artery, and supplies the upper six intercostals spaces;

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The inferior anterior intercostal arteries (arteriae intercostales anteriores inferiores)

arise from the musculophrenic artery (a terminal branch of the internal thoracic artery), and
supplies the intercostals spaces between 6th to 9th.
The lower two spaces contain only posterior intercostal arteries.

Fig. 1-8. Branches of the internal thoracic artery. Posterior view on the intercostal spaces
and sternum

All anterior intercostal arteries pass laterally near the inferior margin of the rib and
anastomose with the posterior intercostal artery. The first two of the anterior intercostal
arteries are situated between the internal intercostal muscles anteriorly and the parietal
pleura posteriorly, however the next four arteries are located between the same muscles
anteriorly and the transverse thoracic muscle posteriorly.

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Right supreme intercostal a. Left supreme intercostal a.

from right costocervical trunk from left costocervical trunk

1st aortic 1st aortic

1 inter - inter- 1
costal costal
2 2

3 3
Right posterior
intercostal 4 4
are larger
5 5
6 6
Aorta is situated
on left side of the 7 7
vertebral column 8 8

9 9

10 10
11 11
S.C. S.C.

Median plane

Fig. 1-9. Posterior intercostal arteries as branches of the thoracic aorta (3-11) +
S.C.= subcostal artery below last rib

The posterior intercostal arteries (arteriae intercostales posteriores) arise from the
posterolateral surface of the thoracic aorta, except the first two, which arise from the
superior intercostal artery (branch of the costocervical trunk).
(!) the 1st & 2nd posterior intercostal arteries arise from the supreme intercostal artery (a
branch of the costocervical trunk).
(!!) the remainder of the posterior intercostal arteries arise from the posterolateral surface
of the thoracic aorta (descending aorta).

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All posterior intercostal arteries run together with the intercostal nerve and intercostal vein
in the following order from top to bottom: vein, artery and nerve. Relations between vein,
artery and nerve (VAN) are shown below:
VEIN is located superiorly
ARTERY is situated between vein & nerve
NERVE is located inferiorly

These structures form the vasonervous fascicle (VAN). VAN occupies the costal groove
and is situated between the internal intercostal membrane externally, the parietal pleura
internally, and after that, between the internal intercostal and innermost intercostal
muscles.
Each posterior intercostal arteries gives off the posterior or dorsal branch (ramus
posterior), which lies with the dorsal branch of the spinal nerve and gives off:
 medial cutaneous branch
 lateral cutaneous branch
 spinal branch
The dorsal branches supplies the spinal cord, vertebral column, and muscles of the back
and skin. Next from each posterior intercostal artery arises the collateral branch of the
lateral cutaneous branch (with the lateral mammary branches), which supplies muscles

and skin of the lateral thoracic wall. The posterior intercostal artery anastomoses around
the midclavicular line with the anterior intercostal artery.

Fig. 1-10. Structures of the nervovascular bundle located: A — at the proximal

aravetebral level (see Fig. 1-7), B — at the distal paravetebral level (see Fig. 1-7) –
lateral to the costal angle

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Fig. 1-11. Structures of the nervovascular bundle located: C — at the axillary line (see
Fig. 1-7), D — at the parasternal line (see Fig. 1-7) – lateral to the sternum

2.2. Veins of the Thoracic Wall

The intercostal veins pass together with the intercostal arteries. Generally, the posterior
intercostal veins return blood to the system of the azygos vein and internal thoracic vein as
follows:
 superior anterior intercostal veins (venae intercostales superiores anteriores)
return blood into the internal thoracic vein.
 inferior anterior intercostal veins (venae intercostales inferiores anteriores) enter
the musculophrenic vein.
 right posterior intercostal veins (venae intrecostales posteriores dextrae) enter
the azygos vein.
 superior left posterior intercostal veins (venae intrecostales posteriores
superiores sinistrae) drain into the accessory hemiazygos vein.
 inferior left posterior intercostal veins (venae intrecostales posteriores) enter the
hemiazygos vein.
 internal thoracic veins (venae thoracicae internae) return blood into the
brachiocephalic vein (!!!).

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Th1

1 1
Right superior 2
. V.
intercostal vein 2 Left superior

R.B
3 . BC
L intercostal vein

C.V
. S.V.C.
3
4 4

5
5
4- 8 Accessory
6 hemiazygos vein
6
7 Th8
7

Azygos vein 8 8

9
9

10
10
9-11 + S.C.

11 Th12 Hemiazygos vein

11

12 12
(S.C.) (S.C.)

Azygos vein Hemiazygos vein

I.V.

Left renal vein

C.

Fig. 1-12. Posterior intercostal veins and their connections with the azygos vein
system. IVC = inferior vena cava, SVC = superior vena cava, R.BC.V. – right
brachiocephalic vein, L.BC.V. – left brachiocephalic vein.

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2.3. Nerves of the Thoracic Wall - Intercostal Nerves

Each thoracic spinal nerve divides into:

 dorsal primary branch (ramus dorsalis), which turns posteriorly and passes
through the muscles of the back and supplies the skin of the back;
 ventral primary branch (ramus ventralis), which passes in the costal groove
under the intercostal vein and artery, almost in the same place as the posterior
intercostal artery (which gives off the lateral cutaneous branch). The eleven pairs of
ventral branches of the thoracic nerves are called the intercostal nerves (nervi
intercostales). Each intercostal nerve gives off the muscular branches, the collateral
branch and the lateral cutaneous branch (ramus cutaneus lateralis), which
divides into two branches (anterior and posterior) and supplies the skin on the
lateral part of the thoracic wall. Not so far from the sternum, the intercostal nerves
turn anteriorly, pass through the intercostal spaces and supply skin on the anterior
thoracic wall as anterior cutaneous branches (rami cutanei anteriores), which are
also divided into two branches (medial and lateral). The lateral cutaneous branches
from Th4-6 of the intercostals nerves gives off the lateral mammary branches.
The anterior cutaneous branches from Th2-4 of the intercostals nerves gives off the
medial mammary branches.
For the purpose of description, intercostal nerves can be divided into the following groups:
1. Typical intercostal nerves are formed by the anterior (ventral) primary branches of the
thoracic spinal nerves from 3rd to 6th .
It gives off the following branches:
 the lateral cutaneous nerve (nervus cutaneus lateralis)
- anterior branch (ramus anterior)
- posterior branch (ramus posterior)
 the anterior cutaneous nerve (nervus cutaneus anterior)
- medial branch (ramus medialis)
- lateral branch (ramus lateralis)
 branches for the intercostal muscles (rami musculares)
 pleural branches (rami pleurales)

2. Atypical intercostal nerves are also formed by the anterior (ventral) primary branches
of the thoracic spinal nerves, but from the 1st , the 2nd , the 7th to the 11th and the 12th
 the 1st thoracic nerve (nervus thoracicus primus) divides unevenly into two
branches:
- superior (larger) to enter the brachial plexus
- inferior supplies structures in the first intercostal space.
 the 2nd thoracic nerve (nervus thoracicus secundus) connects with the brachial
plexus and forms the intercostobrachial nerve which supplies the floor of the axilla
and the antero-medial aspect of the arm.
 the anterior branches of the 7th through the 11th thoracic nerves are called the
thoracoabdominal nerves (nervi thoracoabdominales), because these nerves pass
between the internal abdominal oblique & transverse abdominis muscles and their
terminal branches pierce the posterior and anterior lamina of the rectus sheath. The

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thoracoabdominal nerves supply the anterolateral abdominal wall musculature, the

rectus abdominis muscle and the overlying skin.
 The ventral branch of Th12 is called the subcostal nerve (nervus subcostalis),
because it is located just below the last intercostal space. It is the anterior branch of
the twelfth thoracic nerve. It supplies the anterolateral abdominal wall musculature,
the rectus abdominis and the overlying skin. This nerve is also called the
thoracoabdominal nerve.

All of the intercostal nerves give off many unnamed muscular branches, which supply the
intercostal muscles and many sympathetic fibres (from a ganglion of the sympathetic trunk
- see next parts) to blood vessels and sweat glands.

Medial
cutaneous
Dorsal branch branch Lateral
of thoracic nerve cutaneous
(Posterior primary ramus) branch
Spinal ganglion
Posterior nerve root

Spinal cord

Anterior nerve root Intercostal nerve

Ganglion of (anterior primary ramus)
the sympathetic trunc
Lateral
cutaneous
branch
Pleural branch
Anterior cutaneous branch

Fig. 1-13. Structures of the thoracic nerves

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III. The Diaphragm

3.1. The Structure of the Diaphragm

The diaphragm (diaphragma) is the principal muscle of respiration, which forms a

musculo-fibrous septum between the thoracic and abdominal cavity. During respiration, it
descends as it contracts and ascends as it relaxes. The diaphragm can be divided into two
portions:
peripheral - muscular portion - (pars muscularis)
central – aponeurotic portion - (pars centralis)

The muscular portion of the diaphragm can be subdivided (because of different

attachments) into three parts:
a. the sternal part (pars sternalis) consists of two small muscular slips, which attach to
the posterior surface of the xiphoid process and run posteriorly to the central tendon (Fig.
1-14).
b. the costal part (pars costalis) consists of the muscular slips (wider than in the sternal
part) which are attached to the internal surfaces of the inferior six ribs and their costal
cartilages on the right and left side. Their fibers converge radially to the central tendon.
c. the lumbar part (pars lumbalis) is attached to the anterolateral surface of the lumbar
vertebra L1and L2 on the left side, and L1-L3 on the right side by the musculotendinous
crura. This part is also attached to the median, medial and lateral arcuate ligaments.

The central portion of the diaphragm is called the central tendon (centrum tendineum)
and is partly fused with the pericardium sac. All muscular fibers converge to the central
tendon, which does not have any bony attachment. It is composed of several planes of
fibers, which are integrated, therefore giving additional strength to the structure. The
central tendon is shaped like a three-foil leaf and consists of three divisions (right leaflet -
the largest, central and left - the smallest), separated by slight indentations (Fig. 1-11).

The crura of the diaphragm (crura diaphragmatis) at the beginning integrate with the
longitudinal ligament of the vertebral column.
The right crus (longer than the left) arises from the 1st to the 3rd lumbar vertebrae. It
consists of three muscular bundles between which are located two fissures:
— right lateral fissure
— right medial fissure.
The left crus arises from the 1st to the 2nd lumbar vertebrae. It is formed by the anterior
layer of the lumbar fascia and located over the superior part of the psoas major. It consists
of three muscular bundles (like left crus) between which two fissures are found:
— the left lateral fissure
— the left medial fissure

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Fig. 1-14. Structures of the diaphragm

The arcuate ligaments of the diaphragm (ligamenta arcuata diaphragmatis) are

tendinous arches of the lumbar part of the diaphragm. Between the crura is situated the
aorta. On the anterior surface of the aorta the crura are united by the tendentious band
called:
The median arcuate ligament (ligamentum arcuatum medianum), median lumbocostal
arch (single).

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Laterally to the median arcuate ligament and the aorta are found two additional tendentious
bands:
The medial arcuate ligaments (ligamentum arcuatum mediale), medial lumbocostal
arches (two), one on each side. They are attached at one end to the transverse process of the
first lumbar vertebra, and at the other end connected to the body of L1-L2, and also
integrate with the corresponding crus.
The lateral arcuate ligaments (ligamentum arcuatum laterale) - lateral lumbocostal
arches (also two) are attached on the medial side to the transverse process of L1 and on the
lateral side to the lower margin of the last ribs. Each forms an arch across the quadratus
lumborum muscle.

The function:

The diaphragm is the principal muscle of inspiration (Table 1-1). When the muscular fibers
relax, it is dome-shaped. During inspiration the muscular fibers contract and the central
tendon descends. The right and left domes are flattened. The diaphragm also elevates the
ribs, to which it is attached. As a result, the vertical diameter of the chest is increased. As
the diaphragm descends, it pushes on the abdominal viscera before it and decreases the
intrathoracic pressure, allowing air to enter the lungs. At the end of inspiration the
diaphragm relaxes and the thoracic wall returns to its natural position, causing the air to
leave the lungs. The diaphragm assists the anterior abdominal muscles during micturition,
defecation and parturition.

Table 1-1. The muscles of respiration

MUSCLES OF INSPIRATION MUSCLES OF EXPIRATION

Accessory Sternocleidomastoid Transverse thoracic

Scalene muscles: anterior,

middle and posterior

Principal Diaphragm

External intercostal muscles

Internal intercostal muscles - Internal intercostal - except
intercartilaginous part intercartilaginous part
Abdominal muscles:
Rectus abdominis
External oblique
Internal oblique
Transverse abdominis

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Table 1-2. The diaphragmatic openings

Apertures
of the Localisation Contents
diaphragm

 approximately in the midline, 1.Aorta and thoracic aortic plexus

 posterior to the median arcuate 2.Thoracic duct
Aortic ligament and between the crura, 3. Azygos vein (occasionally)
hiatus  in front of the 12th thoracic
vertebra
 in the central tendon, 1. Inferior vena cava
 in the posterior part of the 2. Phrenico-abdominal branches of
Caval junction between right and the right phrenic nerve
foramen central leaves,
 to the right of the midline at the
level of the 8th thoracic vertebra
 in the muscular portion, 1. Oesophagus
Oesophageal  posterior and left to the vena 2. Anterior and posterior trunk of
hiatus caval foramen, the vagus
 to left of the midline at the level 3. Oesophageal branches of the left
10th thoracic vertebra gastric artery

Lateral fissure Pierces the right crus between the 1. Right lesser splanchnic nerve
of the right lateral and middle muscular bundle 2. Right sympathetic trunk
crus

Lateral fissure Pierces the left crus between the 1. Left lesser splanchnic nerve
of the left lateral and middle muscular bundle 2. Left sympathetic trunk
crus
Medial fissure Pierces the right crus between the 1.Right splanchnic major nerve
of the right medial and middle muscular bundle 2. Azygos vein (occasionally)
crus
Medial fissure Pierces the left crus between the 1.Left splanchnic major nerve
of the left medial and middle muscular bundle 2. Hemiazygos vein
crus
Right 1. Right superior epigastric artery
sternocostal Between the sternal and costal part, 2. Right superior epigastric vein
triangle on the right side
Left 1. Left superior epigastric artery
sternocostal Between the sternal and costal part, 2. Left superior epigastric vein
triangle on the left side

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Fig. 1-15. CT (transverse plane) right and left crus of the diaphragm.
1. aorta, 2. right crus of the diaphragm, 3. left crus of the diaphragm

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3.2. The Arterial Supply of the Diaphragm

The superior surface of the diaphragm is supplied by:
 musculophrenic artery (arteria musculophrenica),
 pericardiacophrenic artery (arteria pericardiacophrenica) both branches from
the internal thoracic artery
 superior phrenic artery (arteria phrenica superior) - branch from the thoracic
aorta.
The inferior surface of the diaphragm is supplied by:
 inferior phrenic artery (arteria phrenica inferior) - branch from the abdominal
aorta which arises just above the celiac trunk.

3.3. The Venous Drainage of the Diaphragm

The musculophrenic and pericardiacophrenic veins (vena musculophrenica et
pericardiophrenica) receive blood from the superior surface of the diaphragm and return it
to the internal thoracic vein (vena thoracica interna).
The inferior phrenic vein (vena phrenica inferior) receives blood from the inferior
surface of the diaphragm and returns it to the inferior vena cava.

3.4. The Lymphatic Drainage of the Diaphragm

The superior surface of the diaphragm is drained by lymphatic vessels, which return lymph
to the phrenic lymph nodes (nodi lymphatici phrenici), and next to the parasternal nodes
and posterior mediastinal lymph nodes.
From the inferior surface of the diaphragm lymph is returned to the lateral aortic lymph
nodes (nodi lymphatici aortales laterales).

 The lymph vessels from the superior and inferior surfaces of the diaphragm
communicate freely !!!

3.5. The Nerve Supply of the Diaphragm

The diaphragm is supplied by motor and sensory fibers from the phrenic nerves (nervus
phrenicus) - ventral branches of C3-C5 of the spinal cord (the longest nerve from the
cervical plexus).
Cervical nerves supply the diaphragm, due to the caudal migration of this muscle during
development. Only the peripheral portion of the diaphragm is supplied by sensory fibers
from the intercostal nerves (nervi intercostales).

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MNEMONIC: for innervation of the diaphragm

A poetic way to remember the innervation of the diaphragm:

C3,4 and 5 keep the diaphragm alive

There are hernias in diaphragm area, which can be divided into hiatal hernias ( 90 % of
all diaphragmatic hernias ) and paraoesophageal hernias (10 % ). The hiatal hernia is
usually connected with gastr–esophageal reflux disesase and can be treated by surgical
procedure.
The diaphragmatic hernia are usually formed at:
 the sternocostal triangle
 the oesophageal hiatus

IV. Axilla

This is a fat filled space between the lateral thoracic wall and the upper limb.

4.1. Walls of the axilla

Its shape is that of a truncated pyramid with apex, base and four walls (Fig. 2-1)
 Apex is bounded by the superior border of the scapula, the outer border of the 1st rib
and the middle third of the clavicle (Fig. 2-2). Through it the axilla communicates with
the posterior triangle of the neck.
 Base is formed by axillary fascia, subcutaneous tissue and skin.
 Anterior wall - contains three muscles arranged in two layers. Superficially - pectoral
major, and deep to this - subclavius pectoral minor enclosed in the clavipectoral fascia.
 Posterior wall - extends lower than the anterior and is composed of three muscles:
subscapularis, latissimus dorsi and teres major (from above downwards).
 Medial wall - comprises the upper five ribs and intercostal spaces, both of which are
covered by slips of the serratus anterior.

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 Lateral wall - the narrow intertubercular groove on the humerus into which muscles of
the anterior and posterior walls are inserted.

Fig. 2-1. Walls of the axilla

4.2. Contents of the axilla

In the axilla are located:

— axillary artery
— axillary vein
— cords and terminal branches of the brachial plexus
— coracobrachialis muscle
— biceps muscle
— axillary lymph nodes and lymph vessels
— fat

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Fig. 2. Apex of the axilla

V. Axillary artery

This is the continuation of the subclavian artery beyond the outer border of the lst rib. It
arches downwards and laterally through the axilla to become the brachial artery at the
lower border of the teres major.

5.1. Relations of the axillary artery

The first part of the artery lies on the first slip of serratus anterior with the axillary
vein and clavipectoral fascia anteriorly and the medial cord of the brachial plexus
posteriorly.
Further lateral the artery lies behind the pectoralis minor, in front of the
subscapularis, medial to the coracobrachialis & lateral to the axillary vein and the
cords of the brachial plexus, which bear the relations their names suggest. Beyond
the pectoralis minor the artery lies on the posterior axillary wall first covered
anteriorly by the pectoralis major and then only by skin. It is surrounded by the
branches of the brachial plexus, with the coracobrachialis lateraly and the axillary
vein medialy.

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Fig. 2-3. Posterior wall of the axilla.

5.2. Branches of the axillary artery

The axillary artery gives the following branches:

 superior thoracic artery - to the anterior thoracic wall.
 thoraco-acromial artery - pierces the clavipectoral fascia and supplies
branches to the anterior axillary wall.
 lateral thoracic artery - supplies lateral thoracic wall (in the female it
contributes to the blood supply of the breast).
 subscapular artery - the largest branch of the axillary artery. It gives off
thoracodorsal artery and circumflex scapular artery. The circumflex scapular
artery passes backwards around the lateral border of the scapula into the
infraspinous fossa. The arteries take part in the anastomosis around the
scapula.
 anterior and posterior circumflex humeral arteries anastomose around the
surgical neck of the humerus.

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 scapular anastomosis: this provides collateral circulation to the upper limb

from the beginning of the subclavian artery to the last part of the axillary
artery by means of anastomotic connections between branches of the
thyrocervical trunk (namely the suprascapular and the deep branch of the
transverse cervical) proximally, and the subscapular artery and its circumflex
branch distally.

VI. Axillary vein

This is the continuation of the brachial vein above the lower border of the teres major. It
passes upwards and medially remaining medial to the axillary artery, to reach the outer
border of the lst rib where it becomes the subclavian vein. Most of its tributaries
correspond to the branches of the axillary artery. The cephalic vein (which it receives)
drains the area supplied by the thoraco-acromial artery and the superficial structures on
the lateral aspect of the limb.

VII. Axillary lymph nodes

There are superficial and deep axillary lymph nodes. The first group contains:
- lateral lymph nodes ( they drain lymph from upper limb, except region which is
supplied by lymph vessels accompaning cephalic vein ),
- pectoral lymph nodes ( they drain lymph from anterior thorax wall ),
Both groups drain to central lymph nodes.
The second group of lymph nodes consist of :
- subscapular lymph nodes ( they drain lymph from upper part of back ),
- central lymph nodes ( they get lymph from 3 groups of lymph nodes mentioned above
and additionally directly from breast ); they drain to apical lymph nodes,
- apical or infraclavicular lymph nodes ( they get lymph from central lymph nodes,
lymph vessels which pass together with cephalic vein and they drain to supraclavicular
lymph nodes ).

Detail knowledge of axillary lymph drainage is very

important for staging and treatment of breast cancer. l

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VIII. The Breast

The breast (mamma) or the mammary gland (glandula mammaria) is the largest
cutaneous gland. It is especially developed in women. Male breast doesn’t perform any
badly function. The main function of the female breast is milk production ( lactation ). It
starts after labour and it is controlled by hormonal factors.
Both breasts are located on the anterior surface of the thoracic wall and they are connected
with superficial layer of thoracic fascia by suspensory ligament of breast. Breasts are
hemispheric or conical shaped. There is nipple on the top of breast and it is surrounded by
areola of nipple. The nipple and areola are darker than normal skin. The areola contains
areolar glands.
The mammary gland consist of glandular and fatty tissue. Young women breasts
contain more glandular tissue and as women age they develop more fatty tissue. The
mammary gland consist of 15 – 20 lobes and every lobe subdivide into lobules. Each lobe
has one lactiferous duct, which ends at the nipple. The lactiferous duct before opening at
the nipple dilates and forms lactiferous sinus.
The breast is supplied by blood from branches of intercostal arteries, lateral thoracic
artery and internal thoracic artery.
Cutaneous nerves which distribute in breast come from intercostal nerves and
supraclavicular nerves ( from cervical plexus ).
Lymph from breast drain to:
- anterior intercostal lymph nodes ( then to supraclavicular lymph nodes ),
- interpectoral lymph nodes ( then to central lymph nodes of axilla),
- posterior intercostal lymph nodes,
- pectoral lymph nodes ( then central lymph nodes of axilla ) – MAIN OUTFLOW
ROUTE OF LYMPH.

Carcinoma of the breast is the most common cancer in women. There are many victims
of this disease all over the world every year. When it is found in early stage it is easy to
treat this lesion. Breast cancer can be diagnosed by self – control, ultrasonography,
mammography and finally biopsy. It usually occurs in upper outer part of breast.
Metastases are found the fastest in axillary lymph nodes. There are some ways of breast
cancer treatment including operation, chemotherapy and radiotherapy.

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IX. Trachea

The trachea (trachea) /windpipe/ is a cartilaginous and membranous cylindrical tube,

flattened posteriorly, which extends from the lower part of the larynx (at level C6) to the
bifurcation of the trachea at the level of the fourth thoracic vertebra, where it divides into
two main bronchi (bronchi principales) / - one to each lung.

Fig. 3-1. Relations of the trachea

The trachea is located in the superior mediastinum, anteriorly to the oesophagus (Fig. 3-1).
The left recurrent laryngeal nerve ascends in the groove between them. Anteriorly the
trachea is crossed by the brachiocephalic trunk and the left brachiocephalic vein.

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There are located on its left side:

 left common carotid artery
 left subclavian artery (branches from aortic arch)
 aortic arch (below them)
There are located on its right side:
 right vagus nerve
 azygos vein

X. Bronchi

1. Localisation of the bronchi

The trachea bifurcates into main stem (primary) bronchi at the carina behind the sternal
angle and at level T4.
Primary bronchi are located posteriorly in the hilus behind
 the pulmonary artery (intermediate)
 the pulmonary veins (anterior)

Left common carotid artery

Brachiocephalic
artery (trunk)
Left subclavian artery

Arch of aorta
(Lies wholly in superior
mediastinum)

Left main bronchus

Right main bronchus

Ascending
aorta

Fig. 3-2. Relations of the bronchi

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2. The right main bronchus

The right main bronchus (bronchus principalis dexter) is larger then the left one and
descends more vertically (Fig.3-3). It divides into three lobar bronchi (Fig. 3-4). The right
main bronchus is most probable a resting-place for aspirated objects because is closer to an
imaginary continuation of the trachea.

3. The left main bronchus

The left main bronchus (bronchus principalis sinister) is longer, narrower and more
horizontal then the right (because the heart is towards the left). It divides into two lobar
(secondary) bronchi.

Fig. 3-3. Division of the trachea

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4. Structure and division of trachea and bronchi

The wall of the trachea and main bronchi are supported by C-shaped rings of cartilage;
posteriorly, the tube is completed by the fibroses membrane. The cartilages are placed
horizontally above each other and connected to each other by the annular ligament -
intercartilaginous ligament.

Thyroid cartilage
Crocoid cartilage
Trachea

Right main bronchus Tracheal cartilages

Superior Left main bronchus

Lobar
bronchus Middle
Superior
Inferior Lobar
bronchus
Inferior

Fig. 3-4. Trachea and divisions of the main bronchi

Two layers of the elastic fibroses membrane cover the outer and inner surfaces of the
cartilages. The trachea and main bronchi are also formed by two layers of muscular fibres -
longitudinal (outer) and transverse (inner between ends of the cartilages). The mucous
membrane, which is located as the innermost layer contains ciliated epithelium and mucous
- secreting cells.

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Segmental
bronchus Cartilages

Alveolar sacs
&
Subsegmental Bronchioles Terminal Respiratory Alveoli
bronchus bronchiole
bronchiole

ACINUS

LOBULE

Fig. 3-4. Divisions of the segmental bronchus

The main bronchi divide into

a. lobar bronchi (bronchi lobales) and next subdivide into
 segmental bronchi (bronchi segmentales). The structure of the wall
changes, as the bronchi divide into smaller parts, subsegmental bronchi
(bronchi subsegmentales). In the walls of segmental and subsegmental
bronchi cartilages are present, mostly at points of branching. At their
terminations subsegmental bronchi divide into ramifications called:
 terminal bronchioles (bronchioli terminales s. alveolares) which
have no cartilages and split into:
 respiratory bronchioles (bronchioli respiratorii) the last
generation with muscular tissue branching into:
* alveolar sacs (sacculi alveolares) and pulmonary alveoli –
aircells- (alveoli pulmonis), which are connected with other
alveoli by alveolar tissue. The muscular tissue disappears.

Terminal bronchioles, respiratory bronchioles, alveolar sacs and pulmonary alveoli make
up structure called a lobule. All lobules are separated by septa which are formed by
connective tissue.
Respiratory bronchioles, alveolar sacs and pulmonary alveoli make up
a structure called an acinus.

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5. The segmental bronchi

A. The right segmental bronchi

The right superior lobar bronchus (bronchus lobaris superior dexter) arises from the
right main bronchus and divides into three segmental bronchi:
 Apical
 Posterior
 Anterior

The right middle lobar bronchus (bronchus lobaris medius dexter) arises from the right
main bronchus and just below the upper lobe bronchus, divides into two segmental
bronchi:
 Medial
 Lateral.

The right inferior lobar bronchus (bronchus lobaris inferior dexter) arises from the right
main bronchus and just below the middle lobe bronchus divides into five segmental
bronchi:
 Superior
 Basal anterior
 Basal posterior
 Basal medial
 Basal lateral.

B. The left segmental bronchi

The left superior lobar bronchus (bronchus lobaris superior sinister) arises from the left
main bronchus and divides into five segmental bronchi:
 Apical
 Posterior
 Anterior
 Superior lingular
 Inferior lingular

The left inferior lobar bronchus (bronchus lobaris inferior sinister) arises from the left
main bronchus and divides into five segmental bronchi:
Superior
 Basal anterior
 Basal posterior
 Basal medial
 Basal lateral.

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A segmental bronchus may branch 5 - 15 times to produce 50 - 70 respiratory bronchioles,

which become alveolar sacs and terminate in the alveoli, constituting the lung parenchyma.
The pulmonary parenchyma represents the expanded terminal portion of the bronchial tree.

Table 3-1. General divisions of main bronchi.

Main bronchus Lobar bronchi Segmental bronchi

Upper 3

RIGHT Middle 2

Lower 5

Upper 5
LEFT
Lower 5

XI. The pleura

1. Structure and division of the pleura

The pleura (pleura) is a serous membrane which surrounds the lung. The pleura has two
layers. The inner layer of the pleura - visceral pleura- invests the external surface of the
lung and the outer layer - parietal pleura - is attached to the internal surface of the thoracic
cavity.
The thoracic cavity is divided into major spaces:
 the right pleural cavity
 the left pleural cavity
 the mediastinum - space between them (interpleural space)
The pleural cavities contain the lungs. All other visceral structures of the thorax are
situated in the mediastinum.
The pleura is divided into two layers:
 The parietal pleura (pleura parietalis)
 The visceral pleura (pleura visceralis)

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2. The parietal pleura

The parietal pleura covers the internal surface of the thoracic wall, superior
surface of the diaphragm, separates the pleural cavity from the mediastinum and forms the
external wall of the pleural sac.
The parietal pleura is subdivided into four parts:
 costal pleura (pleura costalis) covers the internal surfaces of the sternum, costal
cartilages, ribs and intercostal muscles. It is associated with the endothoracic fascia.
Medially it continues as the mediastinal pleura, inferiorly it continues as the
diaphragmatic pleura.
 diaphragmatic pleura (pleura diaphragmatis) covers the superior surface of the
diaphragm except, the space where the pericardium is associated with the
diaphragm.
 mediastinal pleura (pleura mediastinalis) is adjacent to the mediastinum.
 pleural cupula (cupula pleurae) covers the apex of the lung and is formed by the
junction of the costal and mediastinal pleura. It is located above the thoracic inlet,
at the root of the neck, behind the clavicle and first rib.

3. The visceral pleura

The visceral pleura closely covers the lungs and forms the internal wall of the
pleural sac. The visceral pleura invests the outer surfaces of the lung and invaginates into
the fissures of lungs. The visceral pleura is continuous with the parietal pleura at the root of
the lung.
Cervical

Costal pleura

Mediastinal

Diaphragmatic

Fig. 3-5. Visceral pleura

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Between the parietal and visceral pleura is formed the pulmonary ligament (ligamentum
pulmonale). The parietal pleura of the anterior and posterior walls of the thoracic cage is
reflected off of the mediastinal wall towards the lungs.

4. The pleural sac and recesses

The pleural sac (cavitas pleuralis) is the space between the two the layers of the
pleura, and contains normally only a capillary layer of serous fluid. Serous fluid is secreted
by the pleura. Each pleural sac is a closed cavity.
The pleural recess (recessus pleuralis) is empty space in the pleural cavities where
the parietal pleura is in contact with visceral pleura which is not occupied by lungs during
expiration. During deep inspiration, the lung parenchyma expands into recesses, but never
completely fills these spaces.

Costomediastinal recess

Mediastinal visceral pleura Costal parietal pleura

Mediastinal parietal pleura

Costal visceral pleura

Pleural cavity

Fig. 3-6. Transverse section of the pleura.

The pleural recesses are as follows:

 The costodiaphragmatic recess (recesuss costodiaphragmaticus) is the potential
space situated along the inferior margin of the pleura, between the costal and
diaphragmatic pleura, and separated only by a capillary layer of fluid; it forms
inferior complementary space for lung during respiration

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 The costomediastinal recess (recesuss costomediastinalis) is situated along the

anterior margin of the pleura, between the costal and mediastinal pleura; it forms
anterior complementary space for lung during respiration
 The vertebromediastinal recess ( recessus vertebromediastinalis ) is located along
the posterior margin of the pleura, between the costal and mediastinal pleura
 The phrenicomediastinal recess (recesuss phrenicomediastinalis) is located
between the diaphragmatic and mediastinal pleura at the back margin of the pleura.

Costal visceral
pleura

Costal parietal
pleura

Diaphragmatic
visceral pleura
Diaphragmatic
parietal pleura
Rib 8
Costodiaphragmatic recess
of pleural cavity

Rib 10

Fig. 3-7. Sagittal section of the pleura

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5. Lines of pleural reflection

On the right side the following markings define the pleural cavity (Fig.3-8):
 3 cm above medial third of clavicle (cupula)
 to 2nd rib - in midline
 to 6th rib - in sternal line
 to 8th rib - anteriorly in midclavicular line
 to 10th rib - in midaxillary line
 to 12th rib - in paravertebral line
On the left side following markings define the pleural cavity:
 3 cm above medial third of clavicle (cupula)
 to 4th rib - in midline
 to 6th rib - in sternal line
 to 8th rib - anteriorly in midclavicular line
 to 10th rib - in midaxillary line
 to 12th rib – in paravertebral line

Parietal pleura

Viscelar pleura
C.C. 2
Midaxillary line

C.C. 4

Spine Th.10 C.C. 6

SpineTh.12

Rib 8
Rib 10

Fig.3-8. Frontal section of the pleura. CC- costal cartilages.

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6. Nerve supply of the pleura

The costal pleura is innervated by the 1st - 12th intercostal nerves.

The central diaphragmatic pleura and mediastinal pleura is innervated by the phrenic nerve.

Table 3-2. Innervation of the pleura

Nerve supply of the pleura

Parts of the pleura NERVES

Visceral Autonomic pulmonary plexus:

 CNX (parasympathethic & sensory)
 Short splanchnic nerves from the
sympathetic trunk

Parietal
_______________ __________________________________

 Costal Intercostal nerves

 Mediastinal The phrenic nerve

 Diaphragmatic Centrally – the phrenic nerve

Peripherally – five lower intercostal nerves

If air enter the pleural cavity, as the result of any disease or

injury of the visceral pleura or the thoracic wall and the parietal pleura, the lung on that
side collapse immediately. We call this condition pneumothorax.
During some diseases (tuberculosis, pneumonia) we can find abnormally large amounts of
serous fluid in the pleural cavity. This we call hydrothorax and hemothorax or
pyothorax, when the fluid contains also blood or pus. Treatment of this condition is
thoracocentesis, in which needle is inserted through intercostal space to pleural cavity and
fluid is removed.

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XII. The lungs

1. Structure and division of the lungs

The lungs (pulmones) are the paired essential organs of respiration, which are
responsible for oxygenation of venous blood. In the thoracic cavity are situated two lungs;
one placed on each side of the chest and separated from the other by the contents of the
mediastinum. The right lung is larger than the left, mainly due to the cardiac notch of the
left lung. The lung is spongy and elastic in texture and is a conically shaped organ. Each
lung lies in the pleural sac and is attached to the mediastinum at a place called the hilum.
The lung has an apex, base, two surfaces, three borders, a root and a hilum.
Each lung has:
 base (basis) rests on the convex surface of the diaphragm
 apex (apex) extends into the root of the neck about 1 cm above the level of the
clavicle. The apex is covered by the cupula of the pleura. It is crossed by the
subclavian artery, which makes a groove on the mediastinal surface of the lungs.
The lung surfaces are named according to the corresponding thoracic structures:
 diaphragmatic surface (facies diaphragmatica) lies against the diaphragm
 costal surface (facies costalis) is convex and corresponds to the form of the cavity
of the chest
 mediastinal or inner surface (facies mediastinalis) is concave and corresponds to
the pericardium and here the visceral pleura continues as parietal and forms the root
of the lungs. The mediastinal surface contains in its centre the root of the lung –
hilus - which is surrounded by a sleeve of the pleura. The anterior border of the left
lung is deeply indented by the heart to form the cardiac notch.
On the mediastinal surface of the right lung are located:
 right atrial impression (impressio atrialis) or cardiac impression
 superior and inferior vena caval impressiones (sulcus venae cave inferioris et
superioris)
 right brachiocephalic vein (sulcus venae brachiocephalicae dextrae) above groove
for superior vena cava
 groove for azygos vein (sulcus venae azygos )
 oesophageal impression (impressio esophagea) posterior of hilus and pulmonary
ligament
On the mediastinal surface of the left lung are located:
 left ventricular impression (impressio ventricularis sinistri) or cardiac impression
 impression of aortic arch (sulcus aorticus) posterior to the oesophageal impression
 groove for the left brachiocephalic vein (sulcus vena brachiocephalicae sinistrae)
 left subclavian artery impression (sulcus arteriae subclaviae sinistrae)
 oesophageal impression (impressio esophagea)

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The anterior border (margo anterior) is thin and sharp, covers the front of the
pericardium and extends into the costo-mediastinal sinus of the pleura. On the anterior
border of the left lung is present the cardiac notch (incisura cardiaca). This notch is the
anterior margin of the cardiac impression.
The inferior border (margo inferior) of the lungs is the circumference, thin and sharp
and enters into the costodiaphragmatic recess.
The posterior border (margo posterior) is much longer then the anterior border and is
produced by the deep concavity on the sides of the vertebral column.
The root of the lung (radix pulmonis) is situated a little above the middle of the inner
surface of each lung. It is covered by the pleura (here the visceral pleura is continuos with
the parietal pleura).
The roots of the lungs give them attachment and each of them contain the following
structures:
 the main bronchi
 the pulmonary artery
 two pulmonary veins
 the bronchial vessels
 lymph vessels
 nerves
Below these structures, between the two layers of the pleura is situated only connective
tissue. A triangular fold descends vertically to the diaphragm and is called the pulmonary
ligament (ligamentum pulmonale). It gives attachment for the lung into the pericardium.

2. The hilum of the lung

The hilum of the lung (hilus pulmonis) is the space where the lungs are attached to
vessels and air passages; there are structures passing into the lung (main bronchi, arteries,
nerves - efferent fibres) and structures leaving the lung (veins, lymphatic vessels, nerves -
afferent fibres).

Table 3. Contents of the hilum of the lung in the order from superior to inferior

Hilum of the right lung Hilum of the left lung

The right main bronchus and The left pulmonary artery

bronchial vessels
The right pulmonary artery The left main bronchus and
bronchial vessels
The right pulmonary veins The left pulmonary veins

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From anterior to posterior, main structures of the hilum of each lung are situated in the
following order:
the pulmonary veins, pulmonary artery and main bronchus and bronchial vessels

MNEMONIC:

VAB (ant.—>post.) = Vein, Artery, Bronchus

RIGHT LUNG LEFT LUNG

Right superior
lobar bronchus
Pulmonary artery Pulmonary artery
(eparterial bronchus)

Main bronchus

ANTERIOR ANTERIOR
POSTERIOR

Pulmonary veins

Pulmonary veins
Pulmonary
ligament

Fig. 3-9. Medial aspect of the root of the left and right lungs

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3. Lobes of the lung

The lungs are divided into lobes by the fissures.

Upper Upper
Horizontal lobe lobe
fissure

C.C.4
Oblique Middle Oblique
fissure lobe fissure
Lower lobe C.C.6 Lower lobe

Right Left
lung lung

Fig. 3-10. Lobes of the lungs. CC- costal cartilage

The left lung is divided into two lobes :

 the superior lobe (lobus superior)
 the inferior lobe (lobus inferior)

The superior lobe is separated from the inferior one by the oblique fissure (fissura
obliqua), which extends from its costal to medial surface. This fissure is indicated by a line
curving around the thoracic wall from the interval between A, B, C:
A. the 3rd & 4th thoracic vertebrae - in the median posterior line
B. across the 5th intercostal space - in the midaxillary line
C. to the 6th costochondral junction - in the sternal line.

The projection on the right lobe of lung for the oblique fissure is the same. The
superior lobe is situated above the oblique fissure and has a cardiac notch on its anterior
border. The inferior lobe is situated below the oblique fissure and it is larger then the
superior.

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The right lung is divided into three lobes :

 the superior lobe (lobus superior)
 the middle lobe (lobus medialis)
 the inferior lobe (lobus inferior)

The superior and middle lobe are separated from each other by the horizontal fissure
(fissura horizontalis). It is indicated by a line extending from the anterior border of the
right lung along the 4th costal cartilage to the oblique fissure. The superior lobe is located
above the horizontal fissure. The middle lobe is situated between the horizontal fissure
and the oblique fissure. It can be seen only on the anterior surface of the right lung. The
middle and inferior lobes are separated by the oblique fissure, which is just like of the left
lung. The inferior lobe can be identified below this fissure.
Each lobe is divided into a few bronchopulmonary segments, which are supplied by
segmental bronchi. Each bronchopulmonary segment has its own segmental bronchus,
artery and vein.

The bronchopulmonary segments of the right lung

 Superior lobe
 apical segment
 posterior segment
 anterior segment
 Middle lobe
 lateral segment
 medial segment
 Inferior lobe
 superior segment
 medial basal segment
 anterior basal segment
 lateral basal segment
 posterior basal segment

The bronchopulmonary segments of the left lung

 Superior lobe
 apicoposterior segment
 anterior segment
 superior lingular segment
 inferior lingular segment
 Inferior lobe
 superior segment
 medial basal segment
 anterior basal segment
 lateral basal segment
 posterior basal segment

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4. Nerve supply of the lung

 Sympathetic nerves are provided by short splanchnic branches from the left and
right sympathetic chain to the anterior & posterior pulmonary plexuses.
 Parasympathetic nerves pass to the anterior & posterior pulmonary plexuses from
the left and right vagus.

Table 3-4. Sympathetic and parasympathetic regulations of the bronchial tree and
pulmonary vessels

PARASYMPATHETIC: SYMPATHETIC:
CN X - efferent fibres Sympathetic trunk - efferent fibres
VAGUS SHORT SPLANCHNIC
Muscles of BRONCHOCONSTRICTOR BRONCHODILATATOR
the
bronchial
tree
Pulmonary VASODILATATOR VASOCONSTRICTOR
vessels
Glands of SECRETOMOTOR SECRETOINHIBITOR
the
bronchial
tree
MNEMONIC More BLOOD More AIR
Less AIR Less BLOOD

The visceral pleura and subdivisions of the bronchi are innervated by the right and
left pulmonary plexuses. Each plexus is divided into anterior and posterior parts. These
plexuses are formed by fibres from CNX and the sympathetic trunk.
The visceral pleura and bronchial epithelium are supplied by afferent fibres of the
CNX (touch and pain).
The costal and partly the diaphragmatic pleura are supplied (sensory fibre) by the
intercostal nerves. The mediastinal and partly the diaphragmatic pleura are supplied by the
phrenic nerves.
Lung tissue and the visceral pleura are devoided of pain-sensitive nerve endings,
so pain in the chest is always the result of the conditions of the surrounding structures. In
tuberculosis or pneumonia, for example, pain may never be experienced. If a lung disease

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crosses the visceral pleura and the pleural cavity to involve the parietal pleura, pain
becomes a prominent feature.

5. Blood supply of the lung

The arterial vessels of the lungs are disposed in two separate systems:
 The pulmonary arteries (arterie pulmonales) - two branches arise from the
pulmonary trunk and convey deoxygenated blood from the right ventricle to the
lungs. These arteries are connected with the respiratory function of the lung. The
pulmonary trunk arises from the conus arteriosus of the right ventricle and
bifurcates into the left and right pulmonary arteries, supplying the respiratory
(alveolar) parenchyma, carrying deoxygenated blood.
— The right pulmonary artery - RPA (arteria pulmonalis dextra) passes posterior
to the ascending aorta and superior vena cava. It crosses superiorly the right main
bronchus. RPA lies posteriorly to the right superior pulmonary vein at the hilum
and divides into three lobar, and next segmental, arteries.
— The left pulmonary artery - LPA (arteria pulmonalis sinistra) passes anteriorly
to the arch of the descending aorta, where it is connected by a short fibrous band
(the remainder of the ductus arteriosus), the ligamentum arteriosum (ligamentum
arteriosum) to the lower surface of the aortic arch. It crosses the left main bronchus
to lie superiorly. LPA lies posteriorly to the left superior pulmonary vein in the
hilum of the left lung. In the left lung their branches accompany the bronchi and
bronchioles.
 The bronchial arteries (arterie bronchiales) transport oxygenated blood for
nutrition of the lung and arise usually from the thoracic aorta (sometimes from the
upper posterior intercostal arteries) and supply the bronchial tree. This is a
nonrespiratory system.

6. Venous drainage of the lung

The pulmonary veins (venae pulmonales) [oxygenated blood !!!] begin forming after
pulmonary capillaries, as small veins unite to form lager and ultimately form large vessels,
which come into relation with arteries and bronchial tubes (see table 3-3), accompanying
them to the hilum of the organ. The pulmonary veins are short wide vessels formed after
transalveolar gas exchange, transporting oxygenated blood to the left atrium. In the hilum
of the lung they (usually both upper and lower) lie below and in the front of the pulmonary
artery. Venous capillaries combine to form intersegmental veins. The intersegmental veins
unite to form the lobar veins. The right superior & middle lobar veins or left superior &
lingular veins join to form the superior pulmonary veins. The inferior lobar veins continue
as the inferior pulmonary veins.

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The bronchial veins (venae bronchiales) [deoxygenated blood] drain the large
subdivisions of the bronchi. These veins do not receive all blood from the bronchial
arteries (blood partly passes into the pulmonary veins). Usually the hemiazygous vein
drains the left bronchial vein and the azygos vein the right.

7. Lymphatic drainage of the lung

Lymphatic vessels form two plexuses:

 The superficial lymphatic plexus of the lung (plexus lymphaticus pulmonis
superficialis) is situated deep to the visceral pleura. Lymph vessels drain into the
bronchopulmonary lymph nodes (nodi lymphatici bronchopulmonales). These
nodes are situated around the bifurcation of the trachea.
 The deep lymphatic plexus of the lung (plexus lymphaticus pulmonis profundus)
is located in the submucosa of the bronchi and in the peribronchial connective
tissue and from it lymphatic vessels drain to the bronchopulmonary lymph nodes
and to superior and inferior tracheobronchial lymph nodes.
Lymph is mainly returned from superior tracheobronchial lymph nodes by the right
and left bronchomediastinal lymph trunks (trunci lymphatici bronchomediastinales
dexter and sinister) to the right lymphatic duct and thoracic duct.

Bronchial carcinoma is the most common deadly cancer in

Europe and USA. Anatomy of pulmonary lymphatic drainage is fundamental for planning
treatment and estimating the prognosis of this tumour. It can be treated by surgical
operation, chemotherapy or radiotherapy . It is known that smoking is important risk
factor for development of lung cancer.

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HUMAN ANATOMY

PART II

THORAX

BY

Jerzy Gielecki M.D., Ph.D.

Anna Żurada M.D., Ph.D.

Olsztyn 2019
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I. PARTS OF THE HEART ............................................................. 54

II. STRUCTURE OF THE HEART .................................................... 54

1. PERICARDIUM ............................................................................... 55
2. MYOCARDIUM ............................................................................... 56
3. ENDOCARDIUM .............................................................................. 59
III. POSITION OF THE HEART......................................................... 59

IV. CHAMBERS OF THE HEART ..................................................... 61

V. INNERVATION OF THE HEART ................................................. 67

VI. ARTERIAL SUPPLY OF THE HEART........................................ 69

VII. VENOUS DRAINAGE OF THE HEART ..................................... 70
VIII. THE FOETAL CIRCULATION ................................................... 76

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I. Parts of the heart

The heart (cor) is a cone shape, double self-adjusting muscular pump. It is situated in the
middle mediastinum between the lungs and is enclosed by the roots of the great vessels in the
cavity of the pericardium. It propels the blood through the vessels to various parts of the body.
The heart is subdivided by a muscular septum into two halves, left and right, and each half
subdivides into two cavities (Fig. 4-1). The upper cavity is called the atrium and the lower, the
ventricle.

Fig. 2-1. Chambers of the heart

These parts normally work in union. The division of the heart into four chambers is
indicated by grooves upon its surface. For example: the atria are separated from the ventricles
by the atrioventricular groove or coronary groove (sulcus atrioventricularis). The ventricles
are separated by the anterior and posterior interventricular groove (sulcus interventricularis
anterior et posterior), which can be identified on the anterior and posterior surfaces.

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II. Structure of the heart

The heart consists of the following three layers: the pericardium with epicardium,
myocardium and endocardium.

1. Pericardium
The pericardium (pericardium) is the outer conical layer, a double-walled fibro-serous
sac (two layers: external-fibrous pericardium and internal-serous pericardium), which
contains the heart and roots of the great vessels and the pericardial cavity. It is located in the
middle mediastinum.
The pericardium consist of two layers:
— the fibrous pericardium (pericardium fibrosum) is a strong, dense membrane and is
composed of tough fibrous tissue. Its base is fused with the central tendon of the
diaphragm. It is also fused anteriorly to the posterior surface of the sternum by the
superior and inferior sterno-pericardial ligaments. Superiorly, the fibroses pericardium is
also fused with the fibro-elastic coat of the great vessels.
— the serous pericardium (pericardium serosum) can be divided into two layers:
 the visceral pericardium (lamina visceralis pericardii serosi) covers the heart and
forms the epicardium, the external layer of the heart wall. At the point where the
aorta and pulmonary trunk leave the heart, the visceral pericardium is reflected from
the heart and continues as parietal pericardium.
 the parietal pericardium (lamina parietalis pericardii serosi) is fused with the
fibrous pericardium (Fig. 2-2).
— the pericardial cavity (cavum pericardii) is a potential space between the parietal and
visceral layers pericardium which contains a serous fluid. On the posterior surface of the
heart, the reflection of the serous pericardium around the large veins forms a recess
called the oblique pericardial sinus (sinus obliqus pericardi). Also on the posterior
surface of the heart is the transverse pericardial sinus (sinus tranversus pericardii),
which is a short passage that lies between the reflection of the serous pericardium
around the aorta and the pulmonary arteries and the reflection around the large veins.

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Superior vena cava

Fibrous pericardium
Parietal layer
of serous pericardium

Visceral layer
of serous pericardium
(epicardium)

Heart

Pericardiac
cavity (sac)

Diaphragm
Inferior vena cava

Fig. 2-2. Structure of the pericardium

Pericardial effusion is a condition in which fluid accumulate between visceral and parietal
layers of serous pericardium. It can lead to cardiac tamponade, which has following
symptoms: tachycardia, low blood pressure and quiet heart sounds

2. Myocardium
The myocardium is the middle layer of the heart. Muscular fibres are attached to the
fibroses rings, which form the fibrous skeleton of the heart. The fibrous rings surround the
atrio-ventricular (gives attachment for the mitral and tricuspid valves and also for muscular
fibers of the atria and ventricles) and arterial orifices (gives attachment for the great vessels
and semilunar valves). The atrioventricular rings and the aortic arterial ring are connected by
the fibrous tissue.

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Fig. 2-3. Skeleton of the heart

The myocardium is composed of three layers:

— cardiac muscular fibers with:
— the atrial fibers consisting of:
 the superficial fibers (stratum superficiale) -fibers run in the transverse direction
around two atria - common to both
 the deep fibers (stratum profundum), the inner layer -fibers proper to each atrium
run in vertical directions, turn around the superior wall of each atrium and back on
another wall to the fibroses rings.
— the ventricular fibers consist of:
 superficial layer - oblique (stratum superficiale s. obliquum) - the outer layer is
formed by fibers which run obliquely downwards around the two ventricles (only
partly around one ventricle). Some of these fibers change directions to form a
circle around the ventricles. Others turn around the ventricles and ascend, forming
the vertical (inner) layer. At the apex of the heart, some fibers turn suddenly
inward into the interior of the ventricle forming the vortex. It is common to both
ventricles.
 intermediate layer - circular (stratum intermedium s. circulare) - the middle
layer (the strongest) is formed by fibers, which run transversely around each
ventricle.
 deep layer – longitudinal – (stratum profundum s. longitudinale) with apex and
vortex of ventricle.

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- the heart skeleton, which is made by dense connective tissue and consist of:
 the left & right A-V fibrous rings
 the aortic & pulmonary fibrous rings
 the left & right fibrous triangles
 upper membranous portion of interventricular septum
— the conducting system of the heart.
The conducting system of the heart consists of the specialised cardiac muscle cells and
conducting fibres. They initiate the normal heart beat and co-ordinate the contraction of the
four heart chambers. They are present in the sinoatrial node, the atrioventricular node,
atrioventricular bundle and its right and left terminal branches, also in the subendocardial
plexus of Purkinje fibres. The conducting system is comprised of the:
 The sino-atrial node -S-A- (nodus sinoatrialis) is situated at the upper part of the
sulcus terminalis just to the superior vena cava into the right atrium. S-A node
initiates atrial systole. It is the auto rhythmic pacemaker and initiates the
contraction cycle with approximately 72 depolarizations a minute, which is spread
over the atria and the atrioventricular node. From S-A, the cardiac impulse runs
through the atrial myocardium to reach the atrioventricular node.
 The atrioventricular node -A-V- (nodus atrioventricularis), which is located in
the lower part of the interatrial septum just above the attachment of the septal cusp
of the tricuspid valve. A-V node is joined to the S-A node to initiate ventricular
systole. It is located in the myocardium between the crista terminalis and the
opening of the superior vena cava. It initiates the contraction cycle with
approximately 40 depolarizations a minute. Next, the cardiac impulse is
conducted to the ventricles by the atrioventricular bundle.
 The atrioventricular bundle -A-V- bundle (bundle of His) is the muscular
connection between the myocardium of the atria and the myocardium of the
ventricles. The atrioventricular bundle descends behind the septal cusps of the
tricuspid valve to reach the inferior border of the membranous part of the
ventricular septum and divides into right bundle branch and left bundle branch,
one for each ventricle. Each branch usually subdivides into branches which
become continuous with the fibers of the Purkinje plexus.

When the conducting system doesn’t work in proper way, cardiac pacemaker, device, which
generate electrical impulses,is inserted under skin and maintain physiological heart beat.

The septum of the heart consist of the interatrial and the interventricular septum. The
interventricular septum consist of :
- muscular part
- membranous part

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3. Endocardium
Endocardium (endocardium) is the innermost layer lining the cardiac chambers. It is a thin,
smooth endothelium of the ventricles. It is a thin membrane which lines the interior surface of
the heart (it also forms surfaces of the valves) and continues into the lining membrane of the
great vessels.

III. Position of the heart

The heart is situated obliquely, two-thirds to the left and one-third to the right of the
median plane. In adults it measures 5 inches (about 12,5 cm) in length, 3,5 inches (7,5cm) in
width, and 2,5 (5cm) in thickness.
The hearts weight varies from 280 to 340 g in men and from 230 to 280 g in women.
The heart has: a base, apex, three surfaces and four borders.
 The base of the heart (posterior aspect) is located opposite and posteriorly. It lies
from T5/T6 toT8 - and is mainly formed by the left atrium. The ascending aorta
and the pulmonary trunk emerge from the base of the heart whereas the superior
vena cava enters it. Between the base and the vertebral column is situated:
the oesophagus, aorta and thoracic duct.
 The apex is formed by the left ventricle and is situated posteriorly to the left,
fifth intercostal space in adults, just 1 cm medial to the midclavicular line. The
notch of cardiac apex is located 10 mm from apex on the right border. This is a
place where the interventricular grooves (anterior and posterior) connect.
 The sternocostal (anterior) surface is mainly formed by the right ventricle.
 The diaphragmatic (inferior) surface of the heart is formed by both ventricles
and is related to the central tendon of the diaphragm.
 The pulmonary (left) surface of the heart is formed by the left ventricle and is
located in the cardiac notch of the left lung.
 The right border is formed by the right atrium, almost in the same line with the
superior and inferior vena cava. It corresponds to a line, which extends from the
third right costal cartilage to the sixth right costal cartilage.
 The inferior border is mainly formed by the right and partly by the left ventricle
and corresponds to a line drawn from the inferior end of the right border to a
point in the fifth intercostal space, 1 cm to right from the midclavicular line.
 The left border is formed mainly by the left ventricle and corresponds to a line
from the inferior margin of the second left costal cartilage to the left end of
inferior border.
 The superior border is formed by the right and left auricle and superior part of
the right ventricle and corresponds to the line between the superior margin of the
third right costal cartilage to the superior end of the left border.

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Oesophagus
Trachea with left phrenic
and vagus nerves

T.1
Left common carotid artery
Left subclavian artery

Arch of aorta
in superior mediastinum

Pulmonary trunk Root of left lung

Left ventricle
Descending
thoracic aorta

Left phrenic erve

Oesophagus

Diaphragm T.12

Fig. 2-4. Position of the left surface of heart. Left view

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Oesophagus
Trachea with right vagus nerve

T.1 Right phrenic nerve

Right brachiocephalic vein

Vertebral column
Superior vena cava

Arch of azygos vein Manubrium sterni

R.3
Body of sternum
Root of right lung
Right atrium

Right ventricle
R.4

R.5

R.6

Inferior vena cava

T.12 Diaphragm

Fig. 2-5. Position of the right surface of heart. Right view

IV. Chambers of the heart

1. The right atrium
The right atrium (atrium dextrum) receives deoxygenated blood from the following
large vessels:
— the superior vena cava
— inferior vena cava
— coronary sinus
The right atrium has six walls.
 On the superior wall is situated the opening of the superior vena cava, which
returns deoxygenated blood from the upper part of the body.
 On the inferior wall is situated the right atrio-ventricular orifice.

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 On the anterior wall is situated the right auricle, a conical muscular pouch that
overlaps and covers the ascending aorta in the beginning and openings of
smallest cardiac veins.
 On the posterior wall are located two orifices:
* - the first one - the inferior vena cava orifice (returns deoxygenated blood
from lower half of the body) with the nonfunctional after birth valve
of the inferior vena cava (valvae venae cave inferioris).This valve
directs oxygenated blood coming from the placenta into the left atrium
through the foramen ovale, which is closed after birth.
* - the second one - the coronary sinus orifice returns deoxygenated blood
from the veins of the heart. This orifice contains the coronary valve,
which is important during contraction of the atrium, because blood
can’t return to the coronary sinus
 On the medial wall, the interatrial septum (septum interartialis) is located in the
fossa ovalis (fossa ovalis) in adults. This structure corresponds to the foramen
ovale in the fetus, which normally closes after birth.
 On the lateral wall is located the crista terminalis (crista terminalis), which
represents the line of fusion of the sinus venosus of the embryonic with the
primitive proper atrium.

2. The right ventricle

The right ventricle (ventriculus dexter) receives deoxygenated blood from the right
atrium through the atrio-ventricular orifice during relaxation of the ventricle. After the
contraction of the ventricle it moves blood through the pulmonary trunk (pulmonary
orifice) to the lungs. Both of these orifices are separated from each other by the
supraventricular crest (crista supraventricularis).

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Anterior interventricular branch

of left coronary artery

Moderator band

Marginal branch
of right coronary artery

Posterior interventricular branch

of right coronary artery

Fig. 2-6. Walls of the right ventricle

The right atrio-ventricular orifice (ostium atrio-ventricularis dextrum) is surrounded by

a fibrous ring, which is a part of the fibrous skeleton of the heart and gives attachment to the
three cusps of the tricuspid valve (valva tricuspidalis) – anterior, posterior and septal cusps. It
lies behind the left half of the sternum opposite the fourth costal cartilage. The three edges of
the cusps are attached to fibrous threads called the chordae tendinea (chordae tendinea) or
tendinous cords, which arise from the apices of the papillary muscles. Three papillary muscles
(conical shaped) are attached to the wall of the ventricle.

— The anterior papillary muscle (musculus papillaris anterior) is attached to the anterior
wall of the right ventricle. Its chordae tendinea are connected with the anterior and
posterior cusps. Base of the anterior papillary muscle is located on the septomarginal
trabecula. It is connected from the one side with the right border and from the other with
interventricular septum.
— The posterior papillary muscle (musculus papillaris posterior) is attached to the
inferior wall of the right ventricle and its chordae tendinea are connected with the
medial and posterior cusps.
— The septal (medial) papillary muscle (musculus papillaris medialis s. septalis) is
attached to the interventricular septum and its chordae tendinea are connected with
anterior and medial (septal) cusps.

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Posterior Anterior Septal

cusp cusp or medial
cusp
Chordae
tendineae

½ Posterior Anterior Septal ½ Posterior

papillary muscle papillary muscle papillary muscle papillary muscle

Fig. 2-7. Position of the tricuspid valve

The papillary muscles with the chordae tendinea prevent their inversion to the right atrium
during the right ventricle’s contraction.

Cusp

Chordae
tendineae

Papillary muscle

Fig. 2-8. Relations of papilary muscles and cusps

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The pulmonary valve (valva trunci pulmonalis) lies at the apex of the conus arteriosus
(lies behind the medial end of the left costal cartilage and the adjoining part of the sternum)
and consists of three semilunar cusps (anterior, right and left). The cusps lie close to the walls
of the vessel. When the right ventricle is contracts, the cusps are open and when the right
ventricle relaxes, the cusps close to the pulmonary opening. There are nodules on the central
part of the free margin of semilunar cusp and lunules which pass peripherally from the
nodules.
The internal surface of the ventricular wall has irregular muscular elevations, called the
trabeculae carneae, which gives a corsage like a sponge. Conus arteriosus (conus arteriosus)
is the only smooth area that the blood passes as it travels to the pulmonary orifice.

3. The left atrium

The left atrium (atrium sinistrum) receives oxygenated blood from the four pulmonary
veins. We can identify four walls, but thicker then the walls of the right one. There are
pectinate muscles on the wall of left atrium
— On the anterior wall is situated the right auricle which covers the front of the pulmonary
trunk
— On the posterior wall are situated openings of the pulmonary veins (without valves)
— On the inferior wall is situated the left atrio-ventricular orifice with two cusps of the
bicuspid valve (valva bicuspidalis)
— The medial wall - the interatrial septum.

Septal wall and cusp

Anterior cusp Anterior wall and cusp

Marginal branch
of right coronary artery

Posterior wall and posterior cusp

Posterior cusp

Fig. 2-9. Relation of the walls and cusps of the ventricles of the heart

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4. The left ventricle

The left ventricle (ventriculus sinister), is longer, more conically shaped, and three times
more thicker then the right one. The left ventricle receives oxygenated blood from the left
atrium, through the left atrioventricular orifice.
The aortic openings (guarded by the semilunar valves - anterior, right and left posterior) are
located in front of the right side of the atrio-ventricle orifice (lies behind the left half of the
sternum opposite to the third intercostal space). Part of the ventricle, just below the aorta is an
opening called the aortic vestibulum and a wall surrounds this part which is mainly fibroses
(not collapse during diastole). Trabecula carnae are smaller here, but there are more of them.
The cusps contain nodules and lunules like cusps of pulmonary valve.
The left bicuspid valve or mitral valve (valva mitralis) contains two cusps -anterior (larger
one) and posterior. The cusps are connected to the anterior (attached to the anterior wall) and
posterior papillary muscles (attached to the posterior wall) by chordae tendinea.

P S
A
Circumflex
branch
A
P L Left
coronary
R L artery
R
Right A
coronary
artery

Fig. 2-10. Position of the cardiac valves. A- anterior, P- posterior, R- right, L- left, S-septal
(or medial)

Auscultation of the heart valves

When listening to the heart with a stethoscope, two sounds can be heard: lub-dup.
The first sound is produced by the contraction of the ventricles and the closure of the tricuspid
and mitral valves.
The second sound is produced by the sharp closure of the aortic and pulmonary valves. It is
important for each physician to know where to place his/her stethoscope on the chest wall .

— The tricuspid valve is best heard over the right half of the lower end of the body of the
sternum.

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— The mitral valve is best heard over the apex of the heart.
— The pulmonary valve is heard over the medial end of the second left intercostal space.
— The aortic valve is the best heard over the medial end of the second right intercostal
space.

Pulmonary valve
Aortic valve Left brachiocephalic vein

Mitral valve Arch of aorta

Tricuspid valve Pulmonary trunk
Left auricle
1 1

2 2 Left ventricle

3 3

4 4

5 5
6
6

Fig 2-11. Projection of the cardiac valves

V. Innervation of the heart

The heart is innervated by the sympathetic trunk and parasympathetic fibers of the
autonomic nervous system via the cardiac plexuses. Should the blood supply to the
myocardium become impaired, pain impulses reach consciousness via this pathway.
Motor fibers. The heart rate and ejection volume are controlled by the autonomic nervous
system. It has:
 parasympathetic division. The parasympathetic fibers come from the vagus nerves. The
vagus sends fibers over the surface of the heart and to the nodal areas. These preganglionic
fibers synapse with minute postganglionic fibers in the myocardium. Vagal activity slows
the heart rate and reduces the stroke volume.
 sympathetic division. The symphatetic fibers arise from the cervical and upper thoracic
portions of the sympathetic trunks The cardiac accelerator nerves run down the neck to the
heart from superior, middle, and inferior ganglia of the cervical sympathetic chain (trunk).

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Thoracic splanchnic nerves run to the heart from ganglia T1 - T3. Sympathetic activity
accelerates the heart rate and increases stroke volume.
Afferent sensation from the heart runs along the sympathetic pathways via both the cardiac
accelerator nerves of the splanchnic thoracic nerves.
Efferent postganglionic fibers pass to the sino-atrial and atrio-ventricular nodes. These
fibers are also distributed to the regions of the heart as nerve plexuses around the coronary
arteries. Afferent fibers running with the vagus nerves take part in cardiovascular reflexes.
Afferent fibers running with the sympathetic nerves carry nervosa’s impulses that normally do
not reach consciousness.

The pain of the angina pectoris and myocardial infarction radiates from the substernal
region to the neck and along the medial aspect of the arm and forearm. The cardiac pain from
the heart (result due to accumulation of the metabolic products and stimulates pain, but the
heart is insensitive for touch and temperature) is transmitted by the sensory afferent fibers
(the sympathetic cardiac nerves). The axons of the nerves enter spinal cord at the level T1-T5
on the left side. By the synaptic contact, cardiac pain is reflected to the left part of the chest,
shoulder and arm.

To apex
Left coronary artery
Anterior interventricular artery Right aortic sinus

Right coronary artery

Circumflex branch
of left coronary artery Right marginal branch

To apex
Left aortic sinus

Posterior interventricular artery

Fig. 2-12 . Relations and branches of arteries of the heart

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VI. Arterial supply of the heart

Two branches of the ascending aorta, the left and right coronary arteries, which arise from
the left and right aortic sinuses (it is located at the origin of the ascending aorta) and supplies
the heart (Fig. 4-12). These arteries pass anteriorly, on each side of the root of the pulmonary
trunk.
 The right coronary artery (arteria coronaria dextra) artery descends in the coronary
groove between the right atrium and right ventricle to the inferior border and then gives
off:
 the right marginal branch (ramus marginalis dexter) to the apex. the right
marginal branch (ramus marginalis dexter) to the apex
 the conus branch
 atrioventricular branches
 atrial branches
 intermediate atrial branch
After that, turns to the left, passes in the posterior part of the coronary groove and gives
off :
 the posterior interventricular branch (ramus interventricularis posterior). It
supplies posterior wall of the both the ventricles and posterior part of the
interventricular septum by the interventricular septal branches. After giving off this
branch, it then descends in the interventricular groove to the apex of the heart.
 the atrioventricular nodal artery (AV), which one enters the posterior part of the
atrioventricular groove and next passes to the base of the interventricular septum, where
the AV node is located.
 the sinuatrial nodal artery (SA) usually also arises from the right coronary artery
(sometimes arises from the left coronary artery) and supplies the SA node, which is
situated at the superior end of the sulcus terminalis.
 The left coronary artery (arteria coronaria cordis sinistra) after arising from the aorta
lies between the left auricle and the pulmonary trunk. It then further descends into the
coronary groove, where it immediately divides into its terminal branches - the anterior
interventricular branch and the circumflex branch .
 the anterior interventricular branch (ramus interventricularis anterior) descends
into the apex and anastomoses with the posterior interventricular branch. It supplies the
anterior walls of both the ventricles and anterior part of the interventrcular septum by
conus branch, lateral branch and interventricular septal branch.
 the circumflex branch (ramus circumflexus ) passes to the left border and then to the
posterior surface where it lies in the coronary groove. It terminates on the posterior
surface to the left of the posterior interventricular groove and anastomoses with the end
of the left coronary artery. It supplies mainly left part of the heart. It gives off:
 atrial anastomotic branch

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 atrioventricular branches
 left marginal branch
 intermediate atrial branch
 posterior left ventricular branch
 atrial branches
 atrioventricular nodal branch

Angina pectoris is a result of heart ischaemia and it is caused by coronary insufficiency.

Myocardial infarction is a necrosis of part of heart muscle and it is caused by acute coronary
insufficiency too. These diseases can be treated in pharmacological way, by balloon
angioplasty or by coronary bypass surgery.

VII. Venous drainage of the heart

Almost all veins of the heart returns the blood to the coronary sinus, which then drains into
the right atrium. Just only the smallest cardiac veins (venae cordis minime and anterior
cardiac veins) open directly to the chambers of the heart.
 The anterior cardiac veins (venae cordis anteriores) are situated on the anterior surface
of the right ventricle and pass across the coronary groove and return blood directly into
the right atrium.
 The venae cordis minimae (venae cordis minimae) begins in the myocardium and opens
into the chambers of the heart.
The coronary sinus (sinus coronarius) is the main vein of the heart, which is situated in
the posterior part of the coronary groove and receives blood from the following veins:

 The great cardiac vein (vena cordis magna) begins at the apex and ascends in the
anterior interventricular groove, where it lies together with the anterior interventricular
branch (left coronary artery) and then drains into the coronary sinus.
 The posterior left ventricular vein (vena posterior ventriculi sinistri) is located on the
inferior surface and opens into the coronary sinus on the left side of the middle cardiac
vein.
 The middle cardiac vein (vena cardiaca media) begins in a similar maner as mentioned
above, at the apex, but then ascends on the other side in the posterior interventricular
groove (with posterior interventricular branch from right coronary artery) and opens into
the right side of the coronary sinus.

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 The small cardiac vein (vena cordis parva) is situated in the coronary groove (together
with the marginal branch of the right coronary artery) and drains into the coronary sinus
to the right of the middle cardiac vein. Besides there are following veins of heart:
 the left coronary vein
 the oblique vein of left atrium
 the right marginal vein
 the right coronary vein
 the anterior vein of left ventricle
 right atrial veins
 left atrial veins
 atrioventricular veins
 ventricular veins

Anterior cardiac veins

Great cardiac vein

To right atrium

Oblique vein of left atrium

To right atrium Small cardiac vein

Coronary sinus

Middle cardiac vein

Fig. 2-13. Veins of the heart. Relations of the coronary sinus

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VIII. Fetal circulation

The fetus receives blood from the placenta by the umbilical vein, which enters into the
abdomen at the umbilicus, and next passes upward under the liver. It gives off usually two
branches:
 First one, the larger, enters into the right lobe and receives blood from the portal vein.
Blood is then transported by the hepatic veins into the inferior vena cava (IVC).
 Second one, the smaller, is called the ductus venosus continuous to the connection with
the left hepatic vein and next to IVC. The inferior vena cava also receives blood from the
lower extremities and the abdominal wall. IVC transports blood to the right atrium.
 From the right atrium blood is guided by the Eustachian valve into the left atrium through
the foramen ovale.
 In the right atrium this blood is mixed with a little portion of blood returned from the
lungs. The blood then passes into next chamber of the heart - left ventricle, and next into
the aorta. Part of this blood is transported into the head, neck and upper limb. From the
head, neck and upper limb blood is returned by SVC into the right atrium and then into
right ventricle (over the Eustachian valve). From the right ventricle, blood is transported
into the pulmonary arteries but it is shunted along the ductus arteriosus into the aorta
(bypassing the pulmonary circulation and lungs). Ductus arteriosus closes soon after
birth. Aortic blood pass to the rest of body by the thoracic and abdominal aorta. From the
two internal iliac arteries (branches of the common iliac arteries from the abdominal
aorta) arises two umbilical arteries (one on each side) which carry blood into the
placenta. After, when blood is oxygenated and nourished, it is returned to the fetus by the
umbilical vein.

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Oxygenated BLOOD
Deoxygenated

Pulmonary Pulmonary
arteries veins
Foramen ovale

RA LA

RV LV
Aorta and
its branches
Ductus arteriosus
Hepatic vein
Hepatic artery

Portal vein

Inferior Ductus Capillaries of guts

vena cava venosus
Umbilical vein

Umbilical
arteries
Systemic capillaries

Capillaries of placenta

Fig. 2-14. Relations of the foetal circulation

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Oxygenated BLOOD
Deoxygenated

Pulmonary Pulmonary
arteries veins
Pulmonary capillaries

RA LA
Caval veins
RV LV
and their
Right side Left side
tributories Aorta and
of heart of heart
its branches

Systemic capillaries
Fig. 2-15. Relations of the circulation in adult

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 HUMAN ANATOMY

PART III

THORAX

BY

Jerzy Gielecki M.D, Ph.D

Anna Żurada M.D, Ph.D

Olsztyn 2019

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1. MEDIASTINUM ..................................................................................... 80
1.1. DIVISION OF THE MEDIASTINUM ............................................................ 80
2. THE THYMUS ........................................................................................ 83

3. THE OESOPHAGUS.............................................................................. 83

4. THE TRACHEA ..................................................................................... 83

5. THE ARCH OF THE AORTA .............................................................. 83

6. NERVES IN THE MEDIASTINUM ..................................................... 85

6.1. THE VAGUS NERVE ................................................................................ 85
6.2. THE PHRENIC NERVES ........................................................................... 86
7. VEINS IN THE MEDIASTINUM ......................................................... 86
7.1. BRACHIOCEPHALIC VEINS ..................................................................... 86
7.2. SUPERIOR VENA CAVA .......................................................................... 87
7.3. AZYGOS VEIN ........................................................................................ 87
8. MAIN LYMPHATIC VESSELS OF THE THORAX ........................ 88
8.1. THORACIC DUCT ................................................................................... 89
8.2. RIGHT LYMPHATIC DUCT....................................................................... 89

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1. Mediastinum

The mediastinum (mediastinum) is a space which extends between:

— the two pleural sacs on the lateral sides
— the sternum and costal cartilages in front
— the bodies of the thoracic vertebrae posteriorly
— the superior thoracic aperture superiorly
— the diaphragm interiorly

1.1. Division of the mediastinum

The mediastinum is divided for purposes of description into two main parts (Fig.5-1):
 The upper part, the superior mediastinum (mediastinum superius) is situated below the
thoracic inlet and above the horizontal plane passing through the sternal angel and inferior
border of T4 vertebra. It contains :
— retrosternal structures:
 sternohyoid, sternothyroid muscles & the end of the longus coli muscle
 thymus gland
 brachiocephalic veins
 superior vena cava (SVC)
— intermediate structures:
 aorta and its branches
 the vagal nerves
 the phrenic nerves
 cardiac branches of the sympathetic chain
— prevertebral structures:
 prevertebral muscles
 oesophagus
 trachea and its bifurcation at the level of the sternal angle
 thoracic duct
 the left recurrent laryngeal nerve.
 The lower part, the inferior mediastinum (mediastinum inferius) is located below the
horizontal plane passing through the sternal angle and the inferior border of T4 vertebra. The
inferior mediastinum is subdivided into three smaller parts:

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— The anterior mediastinum (mediastinum anterius) is situated between the

sternum, costal cartilages anteriorly and the pericardial sac posteriorly. It
contains:
 lymphatic vessels (ascend from the liver) and nodes
 mediastinal branches of the internal thoracic artery
 sternopericardial ligaments
 fat tissue
— The middle mediastinum (mediastinum medius)
It contains 8 structures:
 heart and pericardium
 ascending aorta
 lower half of superior vena cava and azygos vein
 the two main bronchi
 pulmonary trunk dividing into left & right pulmonary arteries
 the left and right pulmonary veins
 phrenic nerves and the deep part of the cardiac plexus
 the tracheobronchial lymph nodes.
— The posterior mediastinum (mediastinum posterius) is bounded in front by the
pericardium and posteriorly by the bodies of T4 to T12. It contains 6 structures :
 descending thoracic aorta
 the azygos & hemiazygos vein
 the vagus & splanchnic nerves
 the Oesophagus
 the thoracic duct
 posterior mediastinal lymph nodes.

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Superior mediastinum

T.1

T.4

Sternum

Ant. mediastinum
Inferior mediastinum
Middle mediastinum
(divided by
Posterior mediastinum fibrous pericardium)

T.12

Fig. 5-1. Division of the mediastinum

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2. The thymus

The thymus (thymus) is located partly in the neck and partly in the anterior part of the
superior mediastinum. It extends from the fourth costal cartilage to the lower border of the
thyroid gland. The thymus is at full size by the end of the second year and disappears slowly until
puberty, when it is no longer observable. During childhood, it consist of two lateral lobes, which
are connected in the midline. In adulthood it is composed of adipose tissue. It is located behind:
the sternum, pretracheal layer of the neck fascia and the lower part of the sternohyoid and
sternothyroid muscles and in front of the trachea, left brachiocephalc vein, SVC and aortic arch.
Thymus has right and left lobe and it is formed by small lobules of thymus. It is built with
cortex outside and medulla inside. Sometimes thymus has the accessory thymic nodules.
3. The Oesophagus

The Oesophagus (oesophagus) is a muscular canal, which extends from the pharynx to the
stomach. It is about 9 inches (30 cm) in length. It enters into the thorax between the trachea and
vertebral column, and passes posteriorly to the aortic arch. It descends downward and a little to
the left. It consist of following layers going from inside: mucous membrane oesophageal glands,
submucous membrane, muscular layer and adventitia.

4. The trachea

The trachea (trachea) descends from the neck anteriorly to the vertebral column and
Oesophagus and posteriorly to the aortic arch, left brachiocephalic vein and the brachiocephalic
trunk (see lab. session 2). Trachea ends as tracheal bifurcation . There is carina of trachea in this
place.Trachea is formed by tracheal cartilages which are connected by annular ligaments and
posterior wall which is made by trachealis.

5. The arch of the aorta

The arch of the aorta /aortic arch/, (arcus aortae) is a continuation of the ascending aorta
(begins at the level of the second right sternocostal joint) and at the end becomes the descending
thoracic aorta (ends on the left side of the lower border of the fourth thoracic vertebra). The
upper border of this arch is about an inch below the upper margin of the sternum. The aorta in
this part arches generally superoposteriorly and to the left. It then, from the upper point of the
arch, descends posteriorly still remaining to the left. The aortic arch anteriorly crosses the trachea
(just above it's bifurcation ) and Oesophagus and next is situated on the left side of these two
structures. The arch of the aorta is connected with the left pulmonary artery by the ligamentum
arteriosum in adults. It corresponds to the ductus arteriosus in the fetus. It is through this
connection between the aorta and the left pulmonary artery, that blood returns from the
pulmonary artery to the aorta, because the lungs do not work before birth. The ductus arteriosus
is closed normally after birth. The left recurrent laryngeal nerve hooks around the arch from
anterior to posterior.
The arch of the aorta gives off the three following branches:

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1. The brachiocephalic trunk called as the innominate artery (truncus brachiocephalicus)

arises posteriorly to the manubrium of the sternum (at the level T4 or T5) and ascends
superolaterally to the right. It divides (at the level T2 or T3) into the right common carotid and
right subclavian artery.
2. The left common carotid artery (arteria carotis communis sinistra) artery arises
posteriorly to the manubrium (to the left of the brachiocephalic trunk - at the same level), ascends
to the left and returns to the neck.
3. The left subclavian artery (arteria subclavia sinistra) arises from the arch just behind the
left common carotid artery, ascends laterally to the left and is located anteromedially to the left
lung and pleura. It leaves the thorax and enters into the root of the neck.

Branches of the ascending aorta:

- right coronary artery
- left coronary artery
Branches of the thoracic aorta:
- bronchial branches
- oesophageal branches
- pericardiac branches
- mediastinal branches
- superior phrenic branches
- posterior intercostal arteries
- subcostal artery

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6. Nerves in the mediastinum

6.1. The vagus nerve

The vagus nerve (nervus vagus) in the cervical part CNX gives off:
— superior (cervical) cardiac branches (rami cardiaci cervicales superiores).
The thoracic part of the right vagus nerve (pars thoracica nervi vagi dextri) descends from the
neck (anteriorly to the right subclavian artery) through the superior mediastinum on the right side
of the trachea, posteriorly to the right brachiocephalic vein and SCV. Then it passes on the
posterior wall of oesophagus as posterior vagal trunk and formes oesophageal plexus.

It gives off :
— right recurrent laryngeal nerve, which hooks around the right subclavian artery from
anterior to posterior and next ascends to the larynx. It gives off:
— right inferior (cervical) cardiac branches (rami cardiaci cervicales inferiores dextri)
— branches to the left pulmonary plexus
— branches to the oesophageal plexus
— right thoracic cardiac branches (rami cardiaci thoracici dextri)
— bronchial branches

The thoracic part of the left vagus nerve (pars thoracica nervi vagi sinistri) descends from the
neck posterolaterally to the left common carotid artery, and next passes downwards anteriorly to
the aortic arch and posteriorly to the root of the left lung. Then it passes on the anterior wall of
oesophagus as anterior vagal trunk and formes oesophageal plexus.

It gives off:
— left recurrent laryngeal nerve, which hooks around the aortic arch from anterior to posterior
and next ascends to the larynx. It gives off:
— left inferior (cervical) cardiac branches (rami cardiaci cervicales inferiores sinistri)
— branches to the left pulmonary plexus
— branches to oesophageal plexus
— left thoracic cardiac branches (rami cardiaci thoracici sinistri)
— bronchial branches

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6.2. The phrenic nerves

The phrenic nerve (nervus phrenicus) arises from the ventral branches of C3 to C5 nerves.
It is the longest branch of the cervical plexus because of the descending nature of the diaphragm.
Nerves from the cervical plexus supply this muscle.

 The right phrenic nerve (nervus phrenicus dexter) descends on the right side of the
brachiocephalic vein, SVC, and next on the pericardium over the right atrium, anteriorly to
the root of the right lung. It supplies the right part of the diaphragm.
 The left phrenic nerve (nervus phrenicus sinister) descends between the left subclavian
and left common carotid artery and next descends on the left side of the pericardium
anteriorly to the root of the left lung over the left ventricle. It is longer then the right one.

7. Veins in the mediastinum

7.1. Brachiocephalic veins

The right and left brachiocephalic veins called as the innominate veins (vena
brachiocephalica dextra et sinistra) are formed by the union of the internal jugular and
subclavian vein at the level T2 or T3. Branches of the brachiocephalic vein:
- inferior thyroid vein
- unpaired thyroid plexus
- thymic veins
- pericardial veins
- pericardiocophrenic veins
- mediastinal veins
- bronchial veins
- tracheal veins
- oesophageal veins
- vertebral veins
- suboccipital venous plexus
- deep cervical vein
- internal thoracic veins

The right brachiocephalic vein (vena brachiocephalica dextra) from it's origin behind the
right sternoclavicular joint descends to the right side of the upper level of sternal angle of Louis,
where it joins with the left brachiocephalic vein to form SCV. The right brachiocephalic vein
receives the right lymphatic duct .

The left brachiocephalic vein ( vena brachiocephalica sinistra) descends from left to right
anteriorly to the left common carotid artery, left cranial nerve CNX, left phrenic nerve and

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brachiocephalic trunk to join the right brachiocephalic vein. The left one is twice as long as the
right one. The left brachiocephalic vein receives the thoracic duct.

7.2. Superior vena cava

The superior vena cava – SVC - (vena cava superior) receives blood from the two
brachiocephalic veins. It is about 7 cm in length and only the upper part is located in the superior
mediastinum. SVC returns deoxygenated blood from the upper part of the body (the head, neck,
upper limbs and thoracic walls) to the right atrium.

7.3. Azygos vein

The azygos vein (vena azygos) begins at the level L1 or L2 as a branch from the right lumbar
veins. It enters into the thorax through the medial foramen of the diaphragm and ascends along
the right side of the vertebral column to level T5, where it arches behind the root of the right
lung and returns blood to SVC.
Tributaries of the azygos vein:
 the lower ten posterior intercostal veins of the right side
 the right superior intercostal vein, which receives the upper two posterior intercostal veins
of the right side
 the hemiazygos vein
 bronchial veins
 superior phrenic veins
 esophageal veins
 mediastinal and pericardial veins

The hemiazygos vein (vena hemiazygos) begins in the lumbar region as a branch from the
left lumbar veins, passes through the left medial foramen of the diaphragm and ascends on the
left side of the vertebral column to level T9, then crosses vertebral column behind the aorta and
thoracic duct and there joins the azygos vein.
Tributaries of the hemiazygos vein:
 the lower five posterior intercostal vein of the left side
 the oesophageal veins
 mediastinal veins
 occasionally the accessory hemiazygos vein.

The accessory hemiazygos vein (vena hemiazygos accesoria) begins as a junction of the
highest four left intercostal veins and descends returning blood sometimes to the hemiazygos

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vein or crosses the vertebral column at level T8 and empties directly into the azygos vein. It
receives blood from the upper four or five posterior intercostal veins on the left side and the left
bronchial veins.
8. Main lymphatic vessels of the thorax

Lymphatic drainage of the human body is connected with two main lymphatic ducts.

Fig. 3-2. Lymphatic drainage of the human body

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8.1. Thoracic duct

The thoracic duct (ductus thoracicus) begins from the cysterna chyli at the level T12 or L1,
ascends through the aortic hiatus in the diaphragm and lies on the left side of the bodies of the
inferior seven thoracic vertebra between the azygos vein and aorta (Fig. 5-2). It crosses to the left
at level T4-T6, then ascends and empties into the left brachiocephalic vein.
It receives lymph from inferior lymphatic vessels below the diaphragm, posterior mediastinal
lymph nodes, intercostal lymph nodes, and the left side of the: head and neck, upper limbs, lungs,
side of the heart and pericardial sac, trachea and Oesophagus (3/4 of body). It returns lymph to
left venous angle (point of connection of the left subclavian and the left internal jugular veins).
Following trunks emptie to thoracic duct: left subclavian trunk, left jugular trunk and mediastinal
trunks (anterior and posterior).

8.2. Right lymphatic duct

The right lymphatic duct (ductus lymphaticus dexter) receives lymph from the right upper
(supradiaphragmatic) side of body (1/4 of body). It returns lymph to the right venous angle (point
of connection of right subclavian and right internal jugular veins). Following trunks emptie to
right lymphatic duct: right subclavian trunk, right jugular trunk and mediastinal trunks (anterior
and posterior).

Thoracic lymph nodes consist of:

-Paramammary lymph nodes
-Parasternal lymph nodes
-Intercostal lymph nodes
-Prevertebral lymph nodes
-Superior phrenic lymph nodes
-Prepericardial lymph nodes
-Lateral pericardial lymph nodes
-Mediastinal lymph nodes
- Anterior mediastinal lymph nodes
- Posterior mediastinal lymph nodes consist of:
 Pulmonary lymph nodes
 Tracheobronchial lymph nodes
 Superior tracheobronchial lymph nodes
 Inferior tracheobronchial lymph nodes
 Bronchopulomonary lymph nodes
- Paratracheal lymph nodes

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Sympathetic trunk thoracic part

Cervicothoracic ganglion; Stellate ganglion
Ansa subclavia
Inferior cervical cardiac nerve
Vertebral plexus
Thoracic ganglia
Thoracic cardiac branches
Thoracic pulmonary branches
Oesophageal (esophageal) branches
Greater splanchnic nerve
Thoracic splanchnic ganglion
Lesser splanchnic nerve
Renal branch
Least splanchnic nerve

Oesophagus Thoracic duct

Superior vena cava

Lower border of T4

Lower border of T5

Thoracic aorta

Azygos vein

T10
Oesophagus passes
through diaphragm
Oesophagus
T12

Aortic openning of diaphragm

Fig. 5-3. Relation of the thoracic duct

Manual and Review of Gross Anatomy