306 COMMON ILIAC ARTERIES. 



artery. The spermatic arteries are very variable both in origin and 

 number. The right spermatic may be a branch of the renal artery, 

 and the left a branch of the inferior rnesenteric. The supra-renal 

 arteries may be derived from the phrenic or renal arteries. The 

 renal arteries present several varieties in number ; there may be 

 three or even four arteries on one side and one only on the other. 

 When there are several renal arteries on one side, one may arise 

 from the common iliac artery, from the front of the aorta near its 

 lower part, or from the internal iliac. 



COMMON ILIAC ARTERIES. 



The abdominal aorta divides opposite the fourth lumbar vertebras 

 into the two common iliac arteries. Sometimes the bifurcation takes 

 place as high as the third, and occasionally as low as the fifth lum- 

 bar vertebra. The common iliac arteries are about two inches and 

 a half in length ; they diverge from the termination of the aorta, and 

 pass downwards and outwards on each side to the margin of the 

 pelvis opposite the sacro-iliac symphysis, w r here they divide into the 

 internal and external iliac arteries. In old persons the common iliac 

 arteries are more or less dilated and curved in their course. 



The Right common iliac is somewhat longer than the left and 

 forms a more obtuse angle with the termination of the aorta ; the 

 angle of bifurcation is greater in the female than in the male. 



Relations. The relations of the two arteries are different on the 

 two sides of the body. The right common iliac is in relation in 

 front with the peritoneum, and is crossed at its bifurcation by the 

 ureter. It is in relation posteriorly with the two common iliac veins, 

 and externally with the psoas magnus. The left is in relation in 

 front with the peritoneum, arid is crossed by the rectum and superior 

 haemorrhoidal artery, and at its bifurcation by the ureter. It is in 

 relation behind with the left c.ommon iliac vein, and externally with 

 the psoas magnus. 



INTERNAL ILIAC ARTERY. 



The Internal Iliac Artery is a short trunk, varying in length from 

 an inch to two inches. It descends obliquely to a point opposite the 

 upper margin of the great sacro-ischiatic foramen, where it divides 

 into an anterior and a posterior trunk. 



Relations. This artery rests externally upon the sacral plexus 

 and upon the origin of the pyriformis muscle ; posteriorly it is in 

 relation with the internal iliac vein, and anteriorly with the ureter. 



Branches. The branches of the anterior trunk are the 



Umbilical, Ischiatic, 



Middle vesical, Internal pudic. 



Middle haemorrhoidal, 



And in -the female the 

 Uterine, Vaginal. 



