بسم الله الرحمن الرحيم

I. Anterior intercostal veins: - They correspond to the anterior intercostal arteries. - They drain into the venae comitantes of the musculophrenic and internal thoracic arteries.

II. Posterior Intercostal Veins Right side: - 1 st post. intercostal vein  right innominate vein. - 2 nd + 3 rd post. intercostal veins unite to form the right superior intercostal vein  azygos vein. -4 th - 11 th post. intercostal veins  azygos vein. -Subcostal vein  Azygos vein

II. Posterior Intercostal Veins Left side: - 1 st post. intercostal vein  left innominate vein. - 2 nd + 3 rd post. intercostal veins unite to form the superior intercostal vein  left innominate vein. - 4 th – 8 th post. intercostal veins  superior hemiazygos. - 9 th – 11 th post. intercostal vein  inferior hemiazygos vein. - Subcostal vein  inferior hemiazygos vein.

Intercostal Nerves - There are 11 intercostal nerves in the upper 11 intercostal spaces and a subcostal nerve below the last rib (on each side). - Each intercostal nerve arises from the ventral ramus of the corresponding thoracic nerve. - They are classified into: I. Typical Intercostal Nerves II. Atypical Intercostal Nerves: which are the first intercostal nerve, second intercostal nerve and lower five intercostal nerves.

I. Typical Intercostal Nerves

I. Typical Intercostal Nerves Branches 1. Communicating branch to the sympathetic trunk. 2. Collateral branch which runs over the upper border of the rib below. 3. Anterior cutaneous branch. 4. Lateral cutaneous branch which divides into anterior and posterior branches. 5. Muscular branches to the intercostal muscles. 6. Sensory branches to the pleura.

II. Atypical Intercostal Nerves 1. First intercostal nerve - It has a small lat. Cut. Branch to the axilla and ends as a small anterior cutaneous branch. 2. Second intercostal nerve - Its lateral cutaneous branch is called the intercosto- brachial nerve which supplies the base of the axilla and upper part of the medial side of arm and does not divide into anterior and posterior branches. 3. Lower five intercostal nerves - They reach the anterior abdominal wall at the anterior ends of the spaces and supply its structures in addition to the diaphragm.

Arrangement of intercostal nerve and vessels in the costal groove In the posterior end of the space  the nerve is above the vessels. Then, it crosses behind the vessels to continue below them (VAN). In the posterior part, the vessels& nerve are midway between the two ribs. In the lateral& anterior parts  In the costal groove

Applied anatomy: 1. Stab wounds in the posterior part of the intercostal spaces lead to injury of the posterior intercostal nerve and vessels because they run midway between the ribs. -But in the lateral part of the intercostal spaces, they do not injury of the posterior intercostal nerve and vessels because these structures are protected by the costal groove.

Applied anatomy: 2. Needles introduced into the intercostal spaces (to remove collection in the pleura) Site: They are done in the lateral part of the chest wall. Cause: To avoid injury of the posterio intercostal nerve and vessels. (It is also better to be introduced near the rib below).

Thank You Prof.: Dr. Wafaa Abdel-Rahman