504 ARTERIES. 



in close relation with the left side of the aorta, and then passes in front of the 

 left common iliac artery. Its branches are the 



Colica sinistra. Sigmoid. Superior hsemorrhoidal. 



The colica sinistra passes behind the peritoneum, in front of the left kidney, 

 to reach the descending colon, and divides into two branches : an ascending 

 branch, which inosculates with the colica media ; and a descending branch, 

 which anastomoses with the sigmoid artery. From the arches formed by these 

 inosculations, branches are distributed to the descending colon. 



The sigmoid artery runs obliquely downwards across the Psoas muscle to. the 

 sigmoid flexure of the colon, and divides into branches, which supply that part 

 of the intestine ; anastomosing above, with the colica sinistra ; and below, with 

 the superior ha3morrhoidal artery. This vessel is sometimes replaced by three 

 or four small branches. 



The superior hsemorrhoidal artery, the continuation of the inferior mesenteric, 

 descends into the pelvis between the layers of the meso-rectum, crossing, in its 

 course, the ureter, and left common iliac vessels. Opposite the middle of the 

 sacrum it divides into two branches, which descend, one on each side of the 

 rectum, where they divide into several small branches, which are distributed 

 between the mucous and muscular coats of that tube, nearly as far as its lower 

 end ; anastomosing with each other, with the middle hgemorrhoidal arteries, 

 branches of the internal iliac, and with the inferior hsemorrhoidal, branches of 

 the internal pudic. 



The student should especially remark, that the trunk of the vessel descends 

 along the back 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 dis- 

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

 direction, for fear of involving this artery. 



SUPRARENAL ARTERIES. 



The Suprarenal Arteries (Fig. 289) 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 suprarenal cap- 

 sules, 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. 



RENAL 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 

 outwards, so as to form 'nearly a right angle with the aorta. The right is longer 

 than the left, on account of the position of the aorta; it passes behind the in- 

 ferior 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 ureter, the vein being usually in front, the ureter behind. Each 

 vessel gives off some small branches to the suprarenal capsules, the ureter, and 

 the surrounding cellular membrane and muscles. 



SPERMATIC ARTERIES. 



The Spermatic Arteries are distributed to the testes in the male, and to the 

 ovaria in the female. They are two slender vessels, of considerable length, 

 which arise from the front of the aorta, a little below the renal arteries. Each 

 artery passes obliquely outwards and downwards, behind the peritoneum, 

 crossing the ureter, and resting on the Psoas muscle, the right spermatic lying 

 in front of the inferior vena cava, the left behind the sigmoid flexure of the 



