620 THE ARTERIES. 



toward the umbilicus. The abdominal muscles and transversalis fascia are divided, and the peri- 

 toneum raised upward and inward until the Psoas is reached. The artery will be found on the 

 inner side of this muscle, and is to be cleared with a director, especial care being taken on the right 

 side, as here the common iliac veins lie behind the artery. The aneurism needle is to be passed 

 from within outward. But if the aneurismal tumor should extend high up in the abdomen, along 

 the external iliac, it is better to select the posterior or lumbar, by making an incision partly in 

 the abdomen, partly in the loin. The incision is commenced at the anterior extremity of the 

 last rib, proceeding directly downward to the ilium ; it is then curved forward along the crest of 

 the ilium and a little above it to the anterior superior spine of that bone. The abdominal mus- 

 cles having been cautiously divided in succession, the transversalis fascia must be carefully cut 

 through, and the peritoneum, together with the ureter, separated from the artery and pushed 

 aside ; the sacro-iliac articulation must then be felt for, and upon it the vessel will be felt pulsat- 

 ing, and may be fully exposed in close connection with its accompanying vein. On the right 

 side both common iliac veins, as well the inferior vena cava, are in close connection with the 

 artery, and must be carefully avoided. On the left side the vein usually lies on the inner side 

 and behind the artery ; but it occasionally happens that the two common iliac veins are joined on 

 the left instead of the right side, which would add much to the difficulty of an operation in such 

 a case. The common iliac artery may be so short that danger may be apprehended from second- 

 ary haemorrhage if a ligature is applied to it. It would be preferable, in such a case, to tie both 

 the external and internal iliacs near their origin. 



Collateral Circulation. The principal agents in carrying on the collateral circulation after 

 the application of a ligature to the common iliac are the anastomoses of the hsemorrhoidal 

 branches of the internal iliac with the superior haemorrhoidal from the inferior mesenteric ; the 

 anastomoses of the uterine and ovarian arteries and of the vesical arteries of opposite sides ; of 

 the lateral sacral with the middle sacral artery ; of the epigastric with the internal mammary, 

 inferior intercostal, and lumbar arteries ; of the circumflex iliac with the lumbar arteries ; of the 

 ilio-lumbar with the last lumbar artery ; of the obturator artery, by means of its pubic branch, 

 with the vessel of the opposite side and with the deep epigastric. 



Compression of the Common Iliac Arteries. The common iliac arteries are most effi- 

 ciently compressed by Davy's lever. The instrument consists of a gum-elastic tube about two 

 feet long, in which fits a round wooden " lever " considerably longer than the tube. A small 

 quantity of olive oil having been injected into the rectum, the gum-elastic tube, softened in hot 

 water, is passed into the bowel sufficiently far to permit its pressing upon the common iliac artery 

 as it lies in the groove between the last lumbar vertebra and the Psoas muscle. The wooden 

 lever is then inserted into the tube, and the projecting end carried toward the opposite thigh 

 and raised, when it acts as a lever of the first order, the anus being the fulcrum. In cases 

 where the meso-rectum is abnormally short it may be impossible, without unjustifiable force, to 

 compress the artery on the right side. 



Internal Iliac Artery (Fig. 372). 



The internal iliac artery supplies the walls and viscera of the pelvis, the gen- 

 erative organs, and inner side of the thigh. It is a short, thick vessel, smaller 

 in the adult thar the external iliac, and about an inch and a half in length. It 

 arises at the point of bifurcation of the common iliac, and, passing downward to 

 the upper margin of the great sacro-sciatic foramen, divides into two large trunks, 

 an anterior and posterior ; from its point of bifurcation a partially obliterated cord, 

 the hypogastric artery, extends forward to the bladder. 



Relations. In front, with the ureter, which separates it from the peritoneum. 

 Behind, with the internal iliac vein, the lumbo-sacral nerve, and Pyriformis mus- 

 cle. By its outer side, near its origin, with the Psoas magnus muscle. 



PLAN OF THE RELATIONS OF THE INTERNAL ILIAC ARTERY. 



In front. 



Peritoneum. 

 Ureter. 



/- 



Outer side. / \ Inner side. 



Psoas magnus. 



eh i n< I. 



External iliac vein (above). 

 Internal iliac vein. 

 TAimbo-sacral nerve. 

 Sacrum. 



