This document summarizes the anatomy of the thoracic wall. It describes the layers which include skin, superficial fascia, deep fascia and muscles. It outlines the major intrinsic and extrinsic muscles of the thorax. It also details the 11 intercostal spaces, noting they contain intercostal muscles, nerves and vessels. The document explains the anatomy of the intercostal muscles and nerves, as well as the thoracic vasculature including arteries and veins. It concludes with sections on the pleura, pleural recesses and pleural reflections.

2. Contents:
1. skin
2. Superficial fascia
3. Deep fascia
4. muscles
5. Intercostal spaces
6. Internal thoracic vessels
and lymph nodes
7. Endothoracic fascia

4. Superficial fascia:
It contains superficial blood vessels, lymphatic vessels
and the cutaneous nerves.
The cutaneous nerves:
1-The skin of anterior thoracic wall above the second rib is supplied by the
supraclavicular nerves.
2-Anterior wall and lateral wall of thoracic is supplied by anterior
cutaneous branches of intercostal nerves and lateral cutaneous
branches of intercostal nerves.

5. Superficial blood vessels:
1- The anterior perforating branches of the internal thoracic artery supply the
superficial fascia and skin of anterior thoracic wall.
2- The lateral and posterior cutaneous branches of posterior intercostal artery
supply the superficial fascia and skin of the lateral and posterior thoracic wall.

6. Deep structures:
1- The deep fascia:
2- Muscles of thorax:
Extrinsic muscles
1-Pectoralis major
2-Pectoralis minor
3-Serratus anterior
Intrinsic muscles
1-Interercostales externi
2-Intercostales interni
3-Intercostales intimi
4-Transverses thoracis

7. The intercostal spaces:
11 intercostal spaces between 12 ribs.
It contains:
Intercostal muscles
Intercostal nerves
Intercostal vessels

8. The intercostal
muscles:
1-Intercostales
externi:
This muscle arises from the
inferior border of the rib above and
inserts into the superior border of
the rib below.
Its fibers run downwards, forwards
and medially.
Action: These muscles raise the
rib, enlarges the thoracic cavity and
assists in inspiration.

9. 2-Intercostales
interni:
It arises from the upper border of
the rib below and inserts into the
lower border of the rib above.
Its fibers run in opposite and
directed at right angles to that of
the intercostales externi.
Action: These muscles depress
the ribs, diminishes the thoracic
cavity and assists in expiration.

10. 3-Intercostales intimi:
It lies at the middle part of each intercostal space.
The direction of its fibers is as same as that of the intercostal interni. The
both may be differentiated only by the presence of the intercostal nerves and
vessels between them.

11. Human Anatomy, Larry M. Frolich, Ph.D.
INTERCOSTAL MUSCLES
Function in posture, respiration
“COSTAL” = ribs
“intercostal” =
between the ribs

12. The intercostal nerves:
The rami ventral rami of the 1st
to 11th
thoracic spinal nerves are called the
intercostal nerves.
The ventral ramus of 12th
thoracic spinal nerve is called the subcostal nerve.
The first six intercostal nerves supply the following structures related to
respective intercostal spaces:
Skin
Parietal pleura
Intercostal muscles
Levatores costarum and serratus posterior muscles
Seventh to eleventh intercostal nerves supply the following structures:
Skin
Parietal peritoneum
Anterior abdominal muscles including the external oblique, internal oblique,
transversus abdominis and rectus abdominis muscles.

13. Branches of intercostal nerves:
Rami communicates
Collateral branch
Lateral cutaneous branch
Anterior cutaneous branch
Muscular branches
Pleural branches
Peritoneal sensory branches

14. The arteries:
Internal thoracic artery:
It descends into thorax 1.2cm lateral to edge of sternum.
It ends at the sixth costal cartilage by giving following branches:
superior epigastric artery
musculophrenic artery
anterior intercostal artery
pericardiacophrenic artery

15. The veins:
Brachiocephalic veins:
It is formed by union of internal jugular and subclavian veins posterior to
the sternoclavicular joint
Angle of union is termed venous angle
Superior vena cava:
Formed by union of right and left brachiocephalic veins behind the right
sternocostal synchorndrosis of first rib
Runs vertically down on right of ascending aorta
Joined by azygos vein at level of sternal angle
Enters right atrium at lever of lower border of third right sternocostal joint
Collects blood from veins of upper half of body

16. Azygos vein:
 Begins as continuation of right ascending lumbar veins
 Ascending along the right side of vertebral column
 Joins superior vena cava by aching above right lung root at level of T4
to T5
 Tributaries － hemiazygos v. and accessory hemiazygos v.

17. Relationship between
vessels and nerves:
Before reaching to the costal angle, the
intercostal nerve and vessels run in the
middle of the intercostal space and their
arrangement is inconstant, then they lie
between the intercostal intimi and interni
and in the costal groove of the rib
.
Intercostal blood vessels and nerves
runs in the costal groove, the order from
up downward are : vein, artery, nerve.

18. The pleura:
Two kinds
Visceral pleura: Cover the surface of
lungs and dips into the pulmonary fissures.
Parietal pleura: It can be divided into:
Costal pleura: which lines the inner
surface of ribs, costal cartilages and
intercostal spaces.
Diaphragmatic pleura: covers the
superior surface of diaphragm
Cupula of the pleura: extends through
the superior aperture of the thorax into the
root of neck.
Mediastinal pleura: which forms the
lateral part of mediastinum.

19. The Pleural Recess:
The parts of pleural
cavity where the various portions of
parietal pleura meet at an acute angle
and is not occupied by the expanded
lung are call the pleural recess.
The Costodiaphragmatic
Recess:
It is a potential space in
the pleural cavity, at the posterior-most
tips of the cavity, located at the junction
of the costal pleura and diaphragmatic
pleura (in the costophrenic angle).

20. Pleural reflection:
The dome of pleura covers the apex of lung
and extends 2 cm above the medial third of clavicle. It is
basically identical on two sides. The dome of pleura, the
sternal and costal lines of reflection are clinically important.
Above the sternal angle and below the level of fourth costal
cartilage the distance between the two sternal reflections is
larger, these two intervals are called :
1)Superior intermediate region (triangle of thymus)
2)Inferior intermediate region (triangle of pericardium)