CHEST WALL
ANATOMY &
MEDIASTINUM
Luca Novelli, MD
Physician – Pulmonary Medicine Unit
Papa Giovanni XXIII Hospital, Bergamo, IT
Sternum consists of the manubrium
sterni, the corpus sterni, and the
processus xiphoideus
The sternum and cartilage of ribs 1–10
represent the anterior chest wall.
The posterior part consists of 12
thoracic vertebrae and the posterior
aspects of ribs 1–12.
Laterally the chest cavity consists of
ribs 1–12
Free ribs (11th and 12th)
The RIBS are divided into
1. real ribs (costae verae, 1–7) that
have sternal joints
2. false ribs (costae spuriae, 8–10) with
cartilagenous joints to the costal arch
(arcus costalis)
3. free ribs (costae fluctuantes, 11–12)
that end in the soft tissue of the
lateral chest wall. The 12th rib is not
always present.
The ribs move upwards during
inspiration around their rib neck
and downwards during expiration
as well as by the interactions
between the cartilage, sternum,
and costal arch.
The ribs move upwards during
inspiration around their rib neck
and downwards during expiration
as well as by the interactions
between the cartilage, sternum,
and costal arch.
Pectus Excavatum
It is the most common congenital abnormalities of chest wall.
It is characterized by prominent indentation of the lower
sternum, which is usually asymmetric to the right, and
resulting decrease in AP diameter of the rib cage.
The mean pectus index in a normal population is around 2.56.
Haller index is 3.7 (272.4/74.1)
Pectus Carinatum
In contrast to pectus excavatum, pectus
carinatum is an outward protrusion of the
sternum resulting in increased AP diameter of
the thorax. It is the second most common
congenital chest wall deformity
Muscles
Thoracic Wall
Intercostal muscles
1. External intercostal muscle
2. Internal intercostal muscle
3. Innermost intercostal muscle
4. Subcostalis
5. Transversus thoracis
Posterior Thorax
1. Levatores costarum
2. Serratus posterior superior and inferior muscles
Anterior/Superficial Thorax
1. Pectoralis major and minor muscles
2. Subclavius
3. Serratus anterior
Floor
1. Diaphragm
At the neck, the chest is attached by the
three scalene muscles, the intercostal
muscles, and the muscles eminating from
ribs 1 and 2 to the cervical vertebral
bodies (1–7). They are responsible for the
flexion of the upper spine anteriorly and
for lifting the ribs during inspiration
As accessory inspiratory muscles,
ascalene muscles (helps elevate the
first and second ribs) and
sternocleidomastoid muscle (assists in
raising the sternum)
Pectoralis major
The Pectoralis major muscle covers
the upper and lateral part of the
chestwall like a shelf.
It originates from the medial
clavicle, the sternum, the cartilages
of ribs 5–7 as well as from rectus
sheath
The lower edge of the muscle creates
the anterior axillary plication. This
muscle causes a strong adduction and
rotation of the arm and as an auxillary
breathing muscle
Pectoralis minor
muscle is completely covered by the
Pectoralis major muscle. It derives from
the ribs 3–5 and con- nects to the
processus coracoideus of the shoulder.
This muscle pulls the shoulder anteriorly
and downwards and also lifts the chest
as an auxillary breathing muscle
The muscles that make up the thorax wall include the three
intercostal muscles (EXTERNAL, INTERNAL and
INNERMOST or Intercostales intimi), the SUBCOSTALIS
and the TRASVERSUS THORACIS)
Eleven pairs of intercostal muscles
are in each of the intercostal
spaces, arranged from superficial
to deep
The external intercostal muscles
extend from the rib tubercle posteriorly During inspiration, the external
and attach to the costochondral junction intercostals contract and raise the
anteriorly where they continue as thin lateral part of the ribs, increasing
connective tissue aponeuroses known as the transverse diameter of the
the Anterior intercostal membrane thorax
The internal intercostal muscle forms
the intermediate layer. They originate
from the lateral aspect of the costal They depress the ribs and
groove of the rib above and insert into subsequently reduce the thoracic
the superior aspect of the rib below in a volume during forced expiration
direction perpendicular to the external
intercostal muscles
The innermost intercostal muscles
originate from the medial aspect of
the costal groove of the rib above and They are thought to act with the internal
insert onto the internal aspect of the rib intercostal muscle during forced
below. These muscles are lined internally expiration
by the endothoracic fascia right above
parietal pleura
The subcostalis muscles are present in
abundance in the lower regions of the
posterior thoracic wall. They originate
from the internal aspect of one of the
lower ribs and insert onto the internal Both of these muscles aid in
aspect of the second or third rib below. depressing the ribs during forced
expiration.
The transversus thoracis also originate
from the lower posterior sternum, spread
across the inner surface of the thoracic
cage, and inserts onto ribs 2 through 6.
NORMAL EXPIRATION IS
PASSIVE DUE TO ELASTIC
RECOIL OF CHEST WALL
ray, How to read CXR
systematically?
Abbas Ahmed
Chest X-Ray Anatomy
Abbas Ahmed
Chest X-Ray Principles
Abbas Ahmed
Silhouette sign
Abbas Ahmed
Digestive System
Biochemistry MCQs
subcostalis muscles Abbas Ahmed
7 of 23 "
8 of 23
1,424 views
anatomy of the respiratory system 3
Levatores costarum originates from the
transverse processes of C7 to T11 and inserts rib elevation during inspiration
onto the rib below
The serratus posterior superior attaches to
ribs 2 through 5 and elevates them during depress ribs during forced
inspiration whereas the serratus posterior expiration
inferior attaches the vertebrae to ribs 8
through 12
THE MAJOR MUSCLE OF
INSPIRATION COMES FROM
THE DIAPHRAGM
DIAPHRAGM
Be the Terms
first to clipofthis
Useslideand Privacy Policy will apply. If you wish to opt out, please close your SlideS
Recommended
Search pattern for Chest X
ray, How to read CXR
Be the first to clip this slide
systematically?
ArcuateAbbas
ligaments
Ahmed
Chest X-Ray Anatomy
Abbas Ahmed
Chest X-Ray Principles
Abbas Ahmed
Silhouette sign
Abbas Ahmed
Digestive System
Biochemistry MCQs
17 of 23 " Abbas Ahmed
The Diaphragm originates from the lower chest aperture and the vertebral bodies 1–4 of
the lumbar column.
The muscle measuring 3–5 mm thick which creates a dome with a tendon in the center.
Due to the elastic recoil the diaphragm lifts upwards creating the diaphragmatic dome
which is slightly higher on the right side. The excursion can vary 6-7 cm increasing
negative pressure of pleural cavity during inspiration
Besides respiration, the diaphragm also functions to aid abdominal straining and increase
intra-abdominal pressure (i.e. defecation)
Liver in the chest (traumatic herniation)
Diaphragm paralis detected by ultrasound
Rec
Chest wall nerves
The muscles that comprise the thoracic wall
and the posterior thorax are innervated by
the intercostal nerves, which mainly come
from the anterior rami of spinal nerves T1 to
T11.
Each intercostal nerve supplies a dermatome
and a myotome
15 of 23 "
Of note, only a portion of the anterior ramus of spinal
nerve T1 forms the lower trunk
anatomy of of
thethe brachialsystem
respiratory plexus3 1,424 views
...
Innervation to the muscles of the anterior thorax
arises from different branches of, Medical
Abbas Ahmed the student
brachial plexus
+ Follow
# $ %
Phrenic nerve
Innervation to the diaphragm comes from both the
right and left phrenic nerves, which originate from the
anterior rami of C3 to C5.
The phrenic nerve provides both the motor innervation
to allow the diaphragm to contract during inspiration
and sensory innervation to the parietal pleura and
peritoneum covering the central aspect of the
diaphragm
Be the first to clip this slide Recommended
Sear
ray,
syst
Abba
Che
Abba
Che
Abba
Silho
Abba
Dige
Bioc
Abba
Be the first to clip this slide Recommended Be the first to clip this slide
Search pattern for Chest X-
ray, How to read CXR
systematically?
Abbas Ahmed
Chest X-Ray Anatomy
Abbas Ahmed
Chest X-Ray Principles
Abbas Ahmed
Silhouette sign
Abbas Ahmed
Digestive System
Biochemistry MCQs
Abbas Ahmed
Intercostal veins run together with the arteries
and drain into the azygos vein posteriorly and
anteriorly into internal mammary vein into the
subclavian vein.
The remaining anterior intercostal arteries from
the seventh to ninth intercostal spaces come from
the branches of the musculophrenic artery, which
is a terminal branch of the internal thoracic artery
VAN
At the lower edge of the ribs, the structures are found in the
following order: vein, artery, and nerve
Layers of the Chest wall
The anterior and lateral parts of the chestwall in particular are easily accessible
for invasive procedures. Therefore a deep knowledge the anatomy is mandatory.
Three layers can be described:
■ Superficial layer consisting of skin, subcutaneous soft and fatty tissue
(including the mammary gland, which is attached via the membrana sterni with
the sternum
■ Middle layer consisting of muscles of the chest and the abdomen including their
fascias
■ Deep layer consisting of the skeleton, intercostal muscles, blood
vessels/nerves, fascia endothoracica (covers the inner surface of the chest
wall), and parietal pleura.
Thoracentesis
ANATOMICAL REGIONS (defined by the chest wall’s
surface):
1) Ventral:
Regio pectoralis / mammaria, Regio infraclavicularis, Regio
parasternalis, Regio hypchondriaca
2) Lateral:
Regio axillaris
3) Dorsal:
Regio suprascapularis, Regios scapularis, Regio
infrascapularis
ORIENTATION during a examination and/or procedures:
•– Linea sternalis
•– Linea parasternalis
•– Linea medioclavicularis (MCL)
•– Linea axillaris anterior, media, posterior
•– Linea scapularis
•– Linea paravertebralis
MEDIASTINUM
The thoracic mediastinum is the compartment that
runs the length of the thoracic cavity between the
pleural sacs of the lungs. This compartment extends
longitudinally from the thoracic inlet to the superior
surface of the diaphragm.
BOUNDARIES OF MEDIASTINUM
Superior Thoracic outlet
Inferior Diaphragm
Anterior Sternum
Posterior Thoracic vertebrae
Lateral Lungs & pleurae
DIVISIONS OF THE MEDIASTINUM
It is divided by a horizontal plane
It is divided by a horizontal plane
extending from sternal angle to lower
extending from
border of 4 thoracic vertebra into:
SUPERIOR
sternal angle to lower border of 4th thoracic vertebra into:
INFERIOR
1. Superior mediastinum
INFERIOR (S): above the plane
MEDIASTINUM is divided
by heart into:
2. Inferior mediastinum: below the plane,
ANTERIOR
POSTERIOR
Inferior mediastinum is subdivided into:
MIDDLE Mediastinum contains heart
Middle mediastinum (M):contains heart
Anterior mediastinum (A):in front of heart
Superior Mediastinum
4 ❖ Boundaries
❖ Superior: Thor acic out let
❖ Inferior: Hor izontal plane
❖ Anterior: Manubr ium of ster num
❖ Posterior: Upper 4 thor acic ver tebr ae
❖ Lateral: lungs & pleur ae
The Mediastinum Thor
a ci
cduct
❖ Contents :Fr om super ficial❖ to deep:
❖ (1) Gland :Thymus gland
3 It is a thick moveable par tition between r ight & left pleur al
sacs & lungs.
Super ficial
❖ (3) Veins: ❖ It includes all t he st r uct ur es which lie in the inter mediat e
❖ r ight & left br achiocephalic compar t ments of the thor acic cavity
❖ super ior vena cava
❖ (4) Arteries: ❖ Boundaries :
❖ ar ch of aor ta & its br anches
❖ Superior: Thor acic out let: (manubr ium, 1st r ib &T1)
❖ br achiocephalic ar ter y
❖
Int er mediate
Inferior: Diaphr agm
❖ left common car otid
❖ Anterior: St er num
❖ left subclavian
❖ Posterior: 12 Thor acic ver tebr ae thymus
❖ (4) Nerves:
❖ r ight & left vagus
❖ Lateral: Lungs & pleur ae
❖ r ight & left phr enic
❖ (2) Tubes: ❖ Divisions
❖ Tr achea
Deep
❖ Esophagus (most poster ior ) by a hor izontal plane fr om ster nal angle to lower bor der of T4 into:
❖ 1. Super ior mediastinum (1 par t) : above t he plane
(1) Duct: thor acic duct (beside the esophagus)
❖ Lymph nodes 2. Infer ior mediastinum (3 par ts) : below the plane Level of T4
❖ It is the Level of:
Subdivided int o:
1. Ster nal angle
❖ Poster ior mediastinum : behind the hear t 2. Second costal car t ilage
❖ Middle mediastinum : contains the hear t ❖ Why the Level of T4 is important:
1. Bifur cation of tr achea
❖ Anter ior mediast inum : in fr ont of t he hear t 2. Bifur cation of pulmonar y t r unk
3. Beginning & t er mination of ar ch of aor ta
Inferior mediastinum:
5 First part: Posterior Mediastinum
❖ Boundaries:
❖ Superior: Hor izontal plane
❖ Inferior: Diaphr agm
❖ Anterior: Hear t
❖ Posterior: Thor acic ver tebr ae fr om T5 to T12
❖ Lateral: Lungs & pleur ae
Vagus ner
ve
❖ Contents:
❖ Esophagus (most anter ior )
❖ Right & left Vagus nerves: ar ound esophagus
❖ Thoracic duct: poster ior t o esophagus
❖ Azygos vein: poster ior & t o the r ight of esophagus
❖ Descending aorta: post er ior & to the left of esophagus
❖ Right & left sympathetic trunks
❖ Lymph nodes
Helpful Note : it contains one fr om each (ar ter y,vein ,ner ve ,duct ,t ube, tr unk)
Inferior mediastinum:
6 Second part: Middle Mediastinum
❖ Site: Between anter ior & poster ior mediastinum
❖ Contents:
❖ Heart & pericardium
❖ Ascending Aorta
❖ Pulmonary trunk
❖ Superior & inferior vena cava
❖ Right & left pulmonary veins
❖ Right & left phrenic nerves
❖ Lymph nodes Left pulmonary veins
Left phrenic nerve
Right pulmonary veins
Inferior vena cava
Inferior mediastinum:
7 Third part: Anterior Mediastinum
❖ Boundaries:
❖ Superior: Hor izont al plane
❖ Inferior: Diaphr agm
❖ Anterior: Body & xiphoid of ster num
❖ Posterior: Hear t
❖ Lateral: Lungs & pleur ae
❖ Contents:
❖ Thymus gland
❖ Lymph nodes
Note : lymph nodes pr esent in all mediastinum r egion
IMPORTANT NOTE: Ther e ar e six st r uctur e pr esent in mor e than
one r egion in mediast inum
Three in super ior and post er ior mediastinum:
❖ Thor acic duct ,Esophagus , vagus ner ves
Two in super ior and middle mediastinum:
❖ phr enic ner ves ,super ior vena cava
One in super ior and anter ior mediast inum:
❖ Thymus gland
Important structures in Mediastinum
8 Vagus nerve Phrenic nerve Aorta
❖ It is t he 10t h cr anial ner ve. ❖ Root value: C3,4,5 ❖ Ascending aorta:
❖ The r ight vagus descends to t he ❖ Course in thorax: They pass ❖ Beginning: at aor t ic or ifice of left
r ight side of tr achea, for ms t he thr ough the Super ior & Middle ventr icle.
post er ior esophageal plexus & mediastinum ❖ Cour se: in middle mediastinum
cont inues in abdomen as poster ior ❖ The r ight phr enic descends on the ❖ End: continues as ar ch of aor ta
gast r ic ner ve. r ight side of SVC (super ior vena (at level of T4)
❖ The left vagus descends between cava )& hear t . ❖ Arch of aorta:
left common car ot id & left ❖ The left phr enic descends on the ❖ Cour se: in super ior mediast inum
subclavian ar ter ies, for ms the left side of hear t. ❖ End: continues as descending thor acic
anter ior esophageal plexus & ❖ Bot h ner ves ter minate in the aor t a (at level of T4)
cont inues in abdomen as ant er ior diaphr agm ❖ Descending aorta:
gast r ic ner ve. ❖ Supply: ❖ Cour se: in poster ior mediastinum
1) Motor & sensor y fiber s to ❖ End: continues as abdominal aor t a
diaphr agm thr ough diaphr agm
2) Sensor y fiber s to pleur ae &
per icar dium
Lung cancer stadiation by lymph nodes
Lymphatic vessels in thorax
9 ❖ Lymph fr om t he r ight side of t he head, neck, t hor ax, &
upper limb dr ains into the Right lymphatic duct and
ends in t he r ight br achiocephalic vein
❖ Lymph fr om t he lower half of t he body dr ains into t he
Cysterna chyli then t o t he Thoracic duct
❖ Lymph fr om t he left side of t he head, neck, t hor ax, &
upper limb dr ains dir ectly int o t he Thoracic duct
Thoracic duct
Beginning:
It is the cont inuation of Cysterna chyli at the level of L1
Course:
It passes t hr ough the aor tic opening of diaphr agm.
It ascends in the poster ior mediast inum (post er ior to
esophagus).
It ascends in the super ior mediastinum (t o the left of
esophagus).
Tributaries:
It r eceives Lymphatics fr om all body EXCEPT r ight side of(
head & neck, t hor ax, upper limb) as we ment ioned befor e
End:
in the left br achiocephalic vein.
From anatomy to differential diagnosis
Vein occlusion and
infiltration…
