DR. HAYTHEM ALI ALSAYIGH Assistant prof. BOARD CLINICAL SURGICAL ANATOMY F.I.M.B.S.-MB.CH,B COLLEGE OF MEDICINE –UNIVERSITY OF BABYLON IV. Nerves and Blood Vessels of the Thoracic Wall B. Internal thoracic artery : Usually arises from the first part of the subclavian artery and descends directly behind the first six : costal cartilages, just lateral to the sternum.  Gives rise to two anterior intercostal arteries in each of the upper six intercostal spaces and terminates at the sixth intercostal space by dividing into the musculophrenic and superior epigastric arteries.

IV. Nerves and Blood Vessels of the Thoracic Wall  1. Pericardiophrenic artery Accompanies the phrenic nerve between the pleura and the pericardium to the diaphragm. Supplies the pleura, pericardium, and diaphragm (upper surface).  2. Anterior intercostal arteries :Are 12 small arteries , 2 in each of the upper six intercostal spaces that run laterally, 1 each at the upper and lower borders of each space. The upper artery in each intercostal space anastomoses with the  posterior intercostal artery , and the lower one joins the collateral branch of the posterior intercostal artery. Provide muscular branches to the intercostal, serratus anterior, and pectoral muscles.

IV. Nerves and Blood Vessels of the Thoracic Wall  3. Anterior perforating branches :Perforate the internal intercostal muscles in the upper six intercostal spaces, course with the anterior cutaneous branches of the intercostal nerves, and supply the pectoralis major muscle and the skin and subcutaneous tissue over it. Provide the medial mammary branches (second, third, and fourth branches).  4. Musculophrenic artery Follows the costal arch on the inner surface of the costal cartilages. Gives rise to two anterior arteries in the seventh, eighth, and ninth spaces; perforates the diaphragm; and ends in the tenth intercostal space, where it anastomoses with the deep circumflex iliac artery. Supplies the pericardium, diaphragm, and muscles of the abdominal wall.

IV. Nerves and Blood Vessels of the Thoracic Wall  5. Superior epigastric artery : Descends on the deep surface of the rectus abdominis muscle within the rectus sheath; supplies this muscle and anastomoses with the inferior epigastric artery. Supplies the diaphragm, peritoneum, and anterior abdominal wall.  C. Internal thoracic vein: Is formed by the confluence of the superior epigastric and musculophrenic veins, ascends on the medial side of the artery, receives the upper six anterior intercostal and pericardiacophrenic veins, and ends in the brachiocephalic vein.  D. Thoracoepigastric vein :Is a venous connection between the lateral thoracic vein and the superficial epigastric vein. Mediastinum, Pleura, and Organs of Respiration  I. Mediastinum : Is an interpleural space (area between the pleural cavities) in the thorax and is bounded laterally by the pleural cavities, anteriorly by the sternum and the transversus thoracis muscles, and posteriorly by the vertebral column (does not contain the lungs).  Consists of the superior mediastinum above the pericardium and the three lower divisions: anterior, middle, and posterior.

Mediastinum, Pleura, and Organs of Respiration  A. Superior mediastinum Is bounded superiorly by the oblique plane of the first rib and inferiorly by the imaginary line running from the sternal angle to the intervertebral disk between the fourth and fifth thoracic vertebrae. Contains: 1- the superior vena cava (SVC), 2-brachiocephalic veins, 3-arch of the aorta , 4-thoracic duct, 5-trachea , 6-esophagus, 7-vagus nerve, 8-left recurrent laryngeal nerve, 9-and phrenic nerve. 10- Also contains the thymus,( which is a lymphoid organ; is the site at which immature lymphocytes develop into T lymphocytes; and secretes thymic hormones, which cause T lymphocytes to gain immunocompetence. It begins involution after puberty.) Mediastinum, Pleura, and Organs of Respiration  B. Anterior mediastinum : Lies anterior to the pericardium and posterior to the sternum and the transverse thoracic muscles. Contains : 1-the remnants of the thymus gland, 2-lymph nodes, 3-fat, and connective tissue. Mediastinum, Pleura, and Organs of Respiration  C. Middle mediastinum : Lies between the right and left pleural cavities. Contains: 1-the heart, 2-pericardium, 3-phrenic nerves, 4-roots of the great vessels (aorta, 5-pulmonary arteries and veins, and vena cavae), 6-arch of the azygos vein , 7-and main bronchi. Mediastinum, Pleura, and Organs of Respiration  D. Posterior mediastinum (see Structures in the Posterior Mediastinum) : Lies posterior to the pericardium between the mediastinal pleurae. Contains : 1-the esophagus, 2- thoracic aorta, 3- azygos and 4-hemiazygos veins, 5-thoracic duct, 6-vagus nerves, 7- sympathetic trunk, 8-and splanchnic nerves. II. Trachea and Bronchi :-

 A. Trachea : Begins at the inferior border of the cricoid cartilage (C6) as a continuation of the larynx and ends by bifurcating into the right and left main stem bronchi at the level of the sternal angle (junction of T4 and T5).  Is about 9 to 15 cm in length and has 16 to 20 incomplete hyaline cartilaginous rings that open posteriorly toward the esophagus and prevent the trachea from collapsing.  Has the carina , a downward and backward projection of the last tracheal cartilage, which lies at the level of the sternal angle and forms a keel-like ridge separating the openings of the right and left main bronchi.

The carina  The carina: may be examined with a bronchoscope and may be distorted, widened posteriorly, and immobile in the presence of a bronchogenic carcinoma. The mucous membrane over the carina is one of the most sensitive areas of the tracheobronchial tree and is associated with the cough reflex. B. Right main (primary) bronchus

 Is shorter, wider , and more vertical than the left main bronchus; therefore, more foreign bodies that enter through the trachea are lodged in this bronchus or inferior lobar bronchus.  Runs under the arch of the azygos vein and divides into three lobar or secondary (superior, middle , and inferior ) bronchi and finally into 10 segmental bronchi.  The right superior lobar (secondary) bronchus is known as the eparterial (above the artery) bronchus because it passes above the level of the pulmonary artery. All others are the hyparterial bronchi. C. Left main (primary) bronchus  Runs inferolaterally inferior to the arch of the aorta , crosses anterior to the esophagus and thoracic aorta, and divides into two lobar or secondary bronchi , the upper and lower, and finally into 8 to 10 segmental bronchi.  Is also crossed superiorly by the arch of the aorta over its proximal part and by the left pulmonary artery over its distal part. Dilates its lumen by sympathetic nerves and constricts by parasympathetic stimulation.