THE THORACIC AORTA 



587 



crura of the diaphragm, and is thence continued under the name of the abdominal 

 aorta. It is at first situated a little to the left of the vertebral column, but as it 

 descends, approaches the front of the column, at the same time following the back- 

 ward curve of the spine, and at the diaphragm is almost in the middle line. It 

 lies in the posterior mediastinum, having the oesophagus at first a little to the 

 right of it, then in front of it, and just above the tenth thoracic vertebra, where 

 this tube pierces the diaphragm, a little to its left side. 



Fig. 477. — The Arch of the Aorta, the Thoracic Aorta, and the Abdominal Aorta, 

 WITH THE Superior and Inferior Vena Cava and the Innominate and Azygos Veins. 



Right common carotid 



artery 

 Right internal jugular 



vein 



Right lymphatic duct 



Innominate artery 



Right vagus nerve 



Right innominate vein 



Internal mammary vein 



Trunk of the pericardiac 

 and thymic veins 



Superior vena cava 



Azygos vein 



Hemiazygos vein, cross- 

 ing spine to enter vena 

 azygos 



Hepatic veins 



Inferior vena cava 



Right inferior phrenic 

 artery 

 Coeliac artery 



Right middle suprarenal 

 artery 



Right internal spermatic 

 artery 

 Right spermatic vein 



Left common carotid 



artery 

 Left vagus nerve 



Thoracic duct 



Left innominate vein 



Left subclavian artery 



Left superior intercostal 

 vein 



Recurrent (laryngeal) 

 nerve 



Accessory hemiazygos 



vein 

 (Esophagus 



Left upper azygos vein 



(Esophageal branches 

 from aorta 



Hemiazygos vein 



Thoracic duct 



Left inferior phrenic 



artery 

 Left middle suprarenal 



artery 

 Receptaculum chyli 



Superior mesenteric 

 artery 



Left ascending lumbar 



vein 

 Left internal spermatic 

 vessels 



Inferior mesenteric 

 artery 



Relations. — In front it is crossed from above downward by the root of the left lung, by the 

 oesophagus, which separates it from the pericardium and heart, and by the diaphragm. 



Behind, it hes upon the lower seven thoracic vertebrae, and is crossed obhquely opposite 

 the seventh or eighth thoracic vertebra by the the vena hemiazygos (azygos minor) and op- 

 posite the fifth or sixth vertebra by the accessory hemiazygos vein, or by one or more of the 

 intercostal veins. 



On the right side it has, above, the oesophagus and vertebral column; lower down the 

 right pleura and lung. The vena azygos and thoracic duct also lie to the right, but on a some- 

 what posterior plane. 



On the left side it has the left lung and pleura above, and the oesophagus below. The vena 

 hemiazygos and the accessory hemiazygos vein are also to the left, but on a posterior plane. 



