516 SANGUIFEROUS SYSTEM. 



superior cava is double, the coronary vein enters the left 

 superior cava, as in birds. 



The inferior vena cava is single, receives the venous blood 

 of the abdomen, pelvis, and posterior extremities, and con- 

 veys it to the right auricle (142. A. d.}, to be sent with that 

 from the superior cava, through the right ventricle and the 

 pulmonary organs, for respiration. In the legs, as in the 

 arms, the blood is returned by great subcutaneous veins, 

 and by deep-seated venae comites which follow, in anasto- 

 mosing pairs, the course of the large arteries and their 

 branches. The great vena saphena interna and the smaller 

 vena saphena externa, like the cephalic and basilic veins of 

 the arm, follow a superficial course on the leg ; the former 

 ascending along the inner part of the leg, after receiving the 

 superficial epigastric and pudic veins, terminates in the trunk 

 of the femoral vein, as high as the groin; the latter smaller 

 branch, following an exterior and dorsal course, ends in the 

 popliteal vein. The deep seated anterior and posterior 

 tibial veins, and the peroneal branch of the latter, likewise 

 unite to form the popliteal vein. Becoming femoral and 

 external iliac (142. A. 1. 1.), the great vein of the leg, like 

 the corresponding artery, receives the internal iliac vein (142. 

 A. 2. 2.) to constitute, by their union, the trunk of the com- 

 mon iliac (142. A. 3. 3.) 



The large branches of the internal iliac veins, derived 

 from the viscera and parietes of the pelvis, anastomose 

 freely with each other, and form numerous plexuses 

 around these organs. The union of the common iliac 

 veins (142. A. 3. 3.), forms the great trunk of the vena cava 

 inferior (142. A. 4.), which in ascending along the right side 

 of the aorta, to perforate the diaphragm, the pericardium, 

 and the right auricle, receives the middle sacral, the lumbar, 

 the spermatic (142. A. 5.), the renal (142. A. f.), the capsular, 

 and the inferior diaphragmatic veins, and the numerous 

 trunks of the venae hepaticcs (142. A. 8. 9.), which penetrate 

 the inferior cava as it passes behind the liver. The veins 

 from the chylopoietic viscera of the abdomen, form frequent 

 anastomoses, and unite to constitute the two great trunks of 

 the splenic (142. A. 10.), and inferior metenteric (142. A. 11.) 

 veins. The union of these venous trunks forms that of the 

 vtna portce (142. A. 12.), which ramifies through the right 

 (142. A. 14.), and left (142. A. 13.) lobes of the liver, accom- 

 panied by the ramifications of the hepatic artery. The united 



