242 



STRUCTURE OF THE VERTEBRATES 



veins then coalesce and form the superior vena cava which enters 

 the right auricle. 



The metameric costal veins are a part of the azygos, which 

 empties into the superior vena cava. The posterior part of the 

 body is drained by the inferior vena cava (postcava). The ex- 

 ternal and internal iliac veins fuse to form the paired common 

 iliacs, which unite at the level of the sacrum to form the vena 

 cava. This large vessel receives blood from the renal veins, 

 which are joined by the spermatics. Next in order are the 



Carotid 



Subclavian 

 'Aorta 



Hepatic portal 



Coeliac 



■Ant. mesenteric 



Renal 



Post, mesenterii 



Fig. 136. Vascular System of Man (Diagrammatic), 



