THE KIDNEYS 



1355 



divides into four or five branches, which are distributed to its substance. At the hilum these 

 branches lie between the renal vein and ureter, the vein being in front, the ureter behind. Each 

 vessel gives off a small branch to the suprarenal glands, the ureter, and the surrounding tissue and 

 muscles. It has been pointed out by Hyrtl (p. 668) that the renal artery gives off a branch which 

 divides and supplies the dorsal portion of the kidney and a larger branch which divides and sup- 

 plies the ventral portion of the kidney. Between these two vascular systems is a nonvascular 



IV, 



.) Iittralobular ' 

 ) artery and vein 



zone, called by Robinson the exsanguinated renal zone of Hyrtl. It "is one-half inch 

 dorsal to the external border of the kidney." Frequently there is a second renal artery, 

 which is given off from the abdominal aorta at a lower level, and supplies the lower portion of the 

 kidney. It is termed the inferior renal artery. Within the sinus the renal artery divides into 

 four or five branches, about three-fourths of the blood going to the anterior pyramids and the 

 remainder to the posterior pyramids. Each extremity of the kidney is supplied by a branch 



