426 



ARTERIES. 



along the hack part of the rectum as far as the middle of the sacrum before it 

 divides ; this is about a finger's length or four inches from the anus. In disease 



Fig. 226. The Inferior Mesenteric Artery and its Branches. 



Inferior Eemorr/ioiJul 



of this tube, the rectum should never be divided beyond this point in that direc- 

 tion, for fear of involving the artery. 



SUPRA-RENAL ARTERIES. 



The Supra-renal Arteries are two small vessels which arise, one on each side 

 of the aorta, opposite the superior mesenteric artery. They pass obliquely 

 upwards and outwards, to the under surface of the supra-renal capsules, to which 

 they are distributed, anastomosing with capsular branches from the phrenic and 

 renal arteries. In the adult these arteries are of small size ; in the foetus they are 

 as large as the renal arteries. 



EENAL ARTERIES. 



The Renal Arteries are two large trunks, which arise from the sides of the 

 aorta, immediately below the superior mesenteric artery. Each is directed out- 

 wards, so as to form nearly a right angle with the aorta. The right one longer 

 than the left, on account of the position of the aorta, passes behind the inferior 

 vena cava. The left is somewhat higher than the right. Previously to entering 

 the kidney, each artery divides into four or five branches, which are distributed 

 to its substance. At the hilum, these branches lie between the renal vein and 



