420 INTERNAL ILIAC ARTERY. 



The place of division of these arteries is subject to great variety. In two thirds of 

 a large number of cases, it ranged between the middle of the last lumbar vertebra and 

 the upper margin of the sacrum ; in one case out of eight it was above, and in one 

 case out of six it was below that space. Most frequently the left artery was found to 

 divide lower down than the right. (R. Quain.) 



The length varies in most instances between an inch and a half and three inches, 

 but it has been seen in some rare cases less than half an inch, and as long as four 

 inches and a half. In one instance recorded by Cruveilhier, (" Anat. descript." v. iii. 

 p. 186,) the right common iliac artery was wanting, and the internal and external 

 vessels of that side arose as distinct branches from the aorta. 



Branches. The common iliac artery often gives off a small unnamed branch to the 

 lymphatic glands, the ureter or the psoas muscle, and sometimes even a larger branch 

 a renal artery, a lumbar, or the ilio-lumbar. 



INTERNAL ILIAC ARTERY. 



The internal iliac artery (hypogastrica, pelvica) extends from the bifurca- 

 tion of the common iliac artery towards the sacro-sciatic foramen, near 

 which, it divides into branches. It is usually about an inch and a half in 

 length, and is smaller than the external iliac in the adult, but the reverse in 

 the foetus. At its origin, the artery lies near the inner border of the psoas 

 muscle ; lower down, it rests against part of the pyriform muscle. Behind 

 it are situated the internal iliac vein, and the communicating branch which 

 passes from the lumbar to the sacral plexus of nerves : in front it is crossed 

 by the ureter, which separates it from the peritoneum. 



BRANCHES. The branches of the internal iliac artery, though constant, 

 and regular in their general distribution, vary much in their origin. They 

 arise, in most instances, from two principal divisions of the parent trunk, 

 of which one is anterior to the other. From the anterior division arise the 

 superior vesical (connected with the pervious portion of the foetal hypo- 

 gastric artery), the inferior vesical, middle haemorrhoidal, obturator, internal 

 pudic, and sciatic arteries, and also, in the female, the uterine and the 

 vaginal arteries. The posterior division gives off the gluteal, the ilio-lumbar, 

 and the lateral sacral arteries. 



PECULIARITIES. Length. The internal iliac artery has been found as short as 

 half an inch, and sometimes as long as three inches, but it is not often less than an 

 inch in length. An instance has been observed in which this vessel was absent, and its 

 branches were derived from a bend of the external iliac artery down into the pelvis 

 (Preparation in Univ. Coll. Mus., London). The lengths of the common iliac and 

 internal iliac arteries bear an inverse proportion to each other the internal iliac 

 being long when the common iliac is short, and vice versa. Moreover, when the 

 common iliac is short, the internal iliac (arising higher than usual) is placed for some 

 distance above the brim of the pelvis, and descends by the side of the external iliac 

 to reach that cavity. 



The place of division of the internal iliac into its branches varies between the upper 

 margin of the sacrum and the upper border of the sacro-sciatic foramen. 



Branches. Sometimes all the branches of the internal iliac artery arise without the 

 previous separation of that vessel into two portions. 



In more than a fourth of R. Quain's cases a branch, corresponding usually to the 

 ilio-lumbar artery, arose before the subdivision of the main trunk. 



HYPOGASTRIC ARTERY. In the foetus, the internal iliac artery, retaining 

 almost the full size of the common iliac, curves forwards from that artery 

 to the side of the urinary bladder, and ascends on the anterior wall of the 

 abdomen to the umbilicus. There the vessels of opposite sides come into 



