THE INTERNAL ILIAC ARTERY. 4S9 



crossing behind it, and the vena cava, resulting from the union of the 

 two others, being on the right side of the artery at its upper end. 



Varieties. — The ])lace oj <^/r/,?/fl» of these ai-teries 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. ISG,) the right common iliac artery was wanting, 

 and the internal and external vessels of that side arose as distmct branches from 

 the aorta. 



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

 to the lymphatic glands, the ui-eter or the psoas muscle, and sometimes even a 

 larger branch — a renal artery, a lumbar, or the ilio-lumbar. 



SURGICAL ANATOMY O? THE COMMON ILIAC ARTERY. 



The common iliac artery may be reached in an operation by dividing the 

 abdominal muscles in the iliac region. The incision may be made, beginning 

 above the middle of Poupart's ligament, and running parallel with that structure 

 towards the anterior superior spine of the ilium, thence curving for two inches 

 towards the umbilicus. In cutting through the muscles, care is to be taken of 

 the deep epigastric and circumflex iliac arteries, and especially of the peritoneum, 

 which, with the subperitoneal fascia and the adlierent ureter, are to be carefully 

 stripped from the iliac and psoas muscles till the artery is reached. The 

 delicate sheath is then scraped through and the ligature applied. 



INTERNAL ILIAC ARTERY. 



The internal iliac artery (art. hypogastrica,) extends from tlie bifur- 

 cation 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 con- 

 stant 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 hypogastric artery), the inferior vesical, middle 

 hfemorrhoidal, 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. 



Varieties. — 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 



