BLOOD VESSELS 



375 



Innominate 



Subclavian. 



brachial . 



Musculo- 

 cutaneous. 



Sinus venosus 



Hepatic 



entering which it receives the dorsolumbar vein from some of 

 the muscles of the back. In the kidney the vein breaks up into 

 capillaries, which are collected, with those of the renal artery, 

 to give rise to the renal veins. Thus it comes about that much 

 of the blood in the renal veins has passed through two sets of 

 capillaries, one in the leg and another in the kidney. Such an 

 arrangement, in which 

 the blood having passed ^<^"dchuiar. Unguai 



through one set of ^'^ternaUugutanl(// y^ 



^ Internal jugular. -y-\^ 



capillaries is then sent subscapular^^ 

 through a second, is 

 called a portal system. 

 The pelvic veins of the 

 two sides lie in the 

 abdominal wall and join 

 to form the anterior ab- 

 dominal vein which runs 

 forwards above the linea 

 alba in the middle of the 

 belly. This vessel re- 

 ceives a small vesical 

 vein from the bladder, 

 several pairs of vessels 

 from the muscles of the 

 abdomen, and a little 

 backward vessel from 

 the heart wall. It ends in 

 front by passing into the 

 liver and there breaking 

 up into capillaries again. 

 The blood from the 

 stomach, bowel, pan- 



Infenor vena cava 



Hepatic portal. 



Right 

 spermatic. 



Renab. 



Dorsolumbar 



Anterior 

 abdominal. 



Rsnal portal. 



PelvLC . 



femoral. 

 Sciatic. 



vessel Joining 

 sciatic to femor'. 



Fig. 292. — A diagram of the venous system of the 



frog. 



creas, and spleen is gathered up into a great hepatic portal vem, 

 which also breaks up in the liver. Thus the liver has a portal 

 system, which is fed both from the anterior abdominal vein and 

 from the hepatic portal vein, and discharges by the hepatic veins 

 into the inferior vena cava. 



Abnormahties in the vascular system, such as the absence of 

 the precaval of one side and its replacement by a transverse 

 connection to that of the other side, are common. 



The red ceUs in the blood (Fig. 293) are biconvex, oval and 



