560 THE BLOOD-VASCULAR SYSTEM. 



point in one case out of eight ; and below it in one case out of six. The left common iliac 

 artery divides lower down more frequently than the right. 



The relative length, also, of the two common iliac arteries varies. The right common iliac 

 was the longer in sixty-three cases, the left in fifty-two, whilst they were both equal in fifty- 

 three. The length of the arteries varied in five-sevenths of the cases examined from an inch 

 and a half to three inches ; in about half of the remaining cases the artery was longer and in 

 the other half shorter, the minimum length being less than half an inch, the maximum four 

 and a half inches. In two instances the right common iliac has been found wanting, the 

 external and internal iliacs arising directly from the aorta. 



Surface Marking. Draw a zone round the body opposite the highest part of the crest 

 of the ilium ; in this line take a point half an inch to the left of the middle line. From this 

 draw two lines to points midway between the anterior superior spines of the ilium and the 

 symphysis pubis. These two diverging lines will represent the course of the common and 

 external iliac arteries. Draw a second zone round the body corresponding to the level of the 

 anterior superior spines of the ilium : the portion of the diverging lines between the two zones 

 will represent the course of the common iliac artery ; the portion below the lower zone, that of 

 the external iliac artery. 



Surgical Anatomy. The application of a ligature to the common iliac artery may be 

 required on account of aneurism or haemorrhage implicating the external or internal iliacs. 

 Now that the surgeon no longer dreads opening the peritoneal cavity, there can be no question 

 that the easiest and best method of tying the artery is by a transperitoneal route. The abdomen 

 is opened by an incision in either the semilunar line or the linea alba ; the intestines are drawn 

 to one side and the peritoneum covering the artery divided. Hie sheath is then opened, and 

 the needle passed from within outward. On the right side great care must be exercised in 



Eassing the needle, since both the common iliac veins lie behind the artery. After the vessel 

 as been tied the incision in the peritoneum over the artery should be sutured. Formerly there 

 were two different methods by which the common iliac artery was tied, without opening the 

 peritoneal cavity : 1, an anterior or iliac incision, by which the vessel is approached more directly 

 from the front ; and 2. a posterior abdominal or lumbar incision, by which the vessel is reached 

 from behind. If the surgeon select the iliac region, a curved incision, from five to eight inches 

 in length according to the amount of fat, is made, commencing just outside the middle of 

 Poupart's ligament and a finger's breadth above it, and carried outward toward the anterior 

 superior iliac spine, then upward toward the ribs, and finally curving inward toward the 

 umbilicus. The abdominal muscles and transvcrsalis fascia are divided, and the peritoneum 

 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 



