THE VEINS. 441 



2. The veins of the kidneys. 



The veins in connection with the kidneys are 

 best dissected in specimens injected from the femoral 

 vein. Their relations may, however, be determined 

 in an uninjected specimen by slitting them open and 

 following them with a seeker. 



The kidneys are a pair of elongated three-lobed 

 bodies, lying against the ventral surface of the ilia, 

 at the sides of the sacrum. 



The general arrangement of the veins is as 

 follows : — 



Two large veins enter each kidney, the femoral 

 and the hypogastric, returning blood from the leg 

 and the intestine respectively. They traverse the 

 kidney and unite within it. The common trunk 

 formed by their union is joined by the renal vein, 

 returning blood from the substance of the kidney 

 itself, and emerges ~ from the inner side of the 

 kidney as the iliac vein, which unites with its fellow 

 of the opposite side to form the posterior vena cava- 



a. The posterior mesenteric vein is a median vein, 



running backwards in the mesentery supporting 

 the rectum : it collects the blood from the hinder 

 part of the small intestine, and from the rectum 

 and cloaca. Opposite the posterior end of the 

 kidneys it receives a small median caudal vein 

 from the tail, and at once divides into the right 

 and left hypogastric veins. 



b. The hypogastric vein of each side is joined by the 



internal iliac vein from the inner surface of the 

 pelvic cavity, and then enters the kidney at its 

 posterior end : it runs forwards through the 

 posterior and middle lobes of the kidney, and 

 joins the femoral vein, in the groove between 

 the middle and anterior lobes. It receives blood 

 from the dorsal and outer portions of these two 

 lobes. 



