THORACIC CAVITY 



47 



almost vertical. It is accompanied on its medial side by the 

 innominate artery, on its lateral side by the right phrenic nerve, 

 and posteriorly by the right vagus nerve. Antero-laterally 

 it is in relation with the anterior margin of the right pleura. 

 The left innominate vein is much longer than the right. 



Spinal medulla 



Trachea 



Oesophagus 



4th thoracic vertebra 



Innominate artery 



Left common carotid 

 Left innominate vein 



Manubrium sterni 



Synchondrosis 



sternalis 



Right pulmonary 



artery 



Pericardial cavity 



Left atrium 

 Aortic valve 



Body of sternum 



Right atrio- 

 vemricular valve 



Wall of right 



ventricle 



(Esophagus 



Diaphragm 

 Descending aorta 



-Xiphoid process 



Liver 



FIG. 21. Sagittal section of the Thorax of an old man. The upper border 

 of the manubrium sterni and the bifurcation of the trachea are lower 

 than in the average adult. 



It passes obliquely to the right and downwards, posterior to the 

 upper half of the manubrium sterni ; it lies posterior to the re- 

 mains of the thymus gland and the lower ends of the sterno-hyoid 

 and thyreoid muscles, and anterior to the three great branches 

 of the aortic arch and the left phrenic and vagus nerves. 



Tributaries. These are (i) the internal jugular vein, (2) 

 the subclavian vein, (3) the vertebral vein, (4) the internal 

 mammary vein, and frequently (5) the inferior thyreoid vein 



