AZYGOS AND ASCENDING LUMBAR VEINS 



663 



Tributaries.— (1) The lower four or five left intercostal veins; (2) the lower 

 end of the accessory hemiazygos vein (sometimes); (3) small left mediastinal 

 veins; and (4) the lower left oesophageal veins. 



The accessory hemiazygos [v. azygos accessorial varies considerably in size, 

 position, and arrangement, and is often continuous with, or drained by, the left 

 superior intercostal vein. It lies in the posterior mediastinum by the left side of 

 the bodies of the fifth, sixth, and seventh or eighth thoracic vertebrae, and is more 



Fig. 523. — The Superior and Inferior Ven^ Cav^, the Innominate Veins, 



AND THE 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 



Vena cava superior 

 Vena azygos 



Vena hemiazygos, cross- 

 ing to enter vena azygos 



Hepatic veins 



Vena cava inferior 



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 nerve 



Accessory hemiazygos 

 (Esophagus 



Accessory hemiazygos 



vein 

 CEsophageal branches 

 from aorta 



Vena hemiazygos 



Thoracic duct 



Left inferior phrenic 

 artery 



Left middle suprarenal 



artery 

 Cisterna chyli 



Superior mesenteric 

 artery 



Left ascending lumbar 



vein 



Left internal spermatic 



vessels 



Inferior mesenteric 

 artery 



or less vertical in direction. It communicates above with the left superior in- 

 tercostal vein, and below either joins the hemiazygos or passes obliquely across 

 the seventh or eighth thoracic vertebra to join the azvgos vein. It crosses the 

 corresponding left intercostal arteries, and is covered by the pleura. 

 _ Tributaries.— (1) The fourth, fifth, sixth, seventh, and sometimes the eighth 

 intercostal veins; and (2) the left posterior bronchial vein. 



The ascending lumbar vein [v. lumbalis ascendens] begins, on either side, in 

 the neighbourhood of the sacral promontory. It is here in free communication, by 



