Posterior Mediastinum Dr. Miral Nagy Fahmy Lecturer Of Anatomy Thoracic Duct It ‘s 45 cm channel. Arises from cisterna chyli( lymph sac in front of L1. It enters the thorax through the aortic opening at T12. It lies between aorta on the left and azygos vein on the right (ATA). At the level of T5, it crosses behind the esophagus to be to the left of it. At the root of the neck ( C7), it arches laterally to open at the junction of left internal jugular and left subclavian veins It drains lymph from below the diaphragm through cisterna chyli. It drains the lymph from the left ½ of the body above the diaphragm through left jugular lymph duct ( lt. ½ of head& neck) , left subclavian lymph duct ( lt. upper limb) and left broncho-mediastinal lymph duct (lt. ½ of the thorax The Esophagus It’s a muscular tube , 25 cm long. It begins at the lower border of cricoid cartilage (C6). It passes through its opening in the diaphragm at (T10) , to end one inch from the midline to the left in the stomach at (T11). Esophagus has 3 parts, cervical , thoracic and abdominal. It has 4 constrictions. At it beginning (6 inches from the incisors). Where crossed by aortic arch (9 inches). Where crossed by left bronchus (11 inches). Where traverses the diaphragm (16 inches). Relations In The Superior Mediastinum Anteriorly: the trachea Posteriorly: the vertebral column. On the Rt. Side: arch of azygos , lung and pleura On the Lt. side: arch of aorta , lung , pleura , thoracic duct and left recurrent laryngeal nerve. Relations In The Posterior Mediastinum Anteriorly: tracheal bifurcation , left bronchus, oblique sinus and diaphragm. T8 T10 Posteriorly : Vertebral column , Thoracic duct at T5, Descending thoracic aorta at T8 – 10 and Azygos vein On the left side: Descending aorta at T5 – 7. Left lung and pleura On the right side: Upper part of azygos vein , Right lung and pleura On the right side : Thoracic duct at T 12, Descending Thoracic Aorta It’s the continuation of the arch at the lower border of T4. It ends at the lower border of T12 ,where it traverses its diaphragmatic opening with the thoracic duct and azygos vein (ATA) Anteriorly: Hilum of the left lung , Esophagus T8 - 10 and diaphragm. Posteriorly : Vertebral column On the left side : T8 Left lung and pleura T10 On the right side: Its lower part related to thoracic duct and azygos vein. Its upper part related to the esophagus T5 – 7. Visceral branches : Coronary arteries, Bronchial arteries, Mediastinal arteries, Esophageal arteries, Pericardial arteries and superior pherinc arteries. The Azygos Vein It’s formed either from the back of I.V.C at L2 (lumbar azygos vein) or by union of right ascending lumbar vein and subcostal vein at T12. Its tributaries : Right ascending lumbar vein and subcostal vein at T12. Right superior intercostal (2,3). Right posterior intercostals (4 -11). Upper & lower hemiazygos. Mediastinal , pericardial and esophageal veins.