THE INTERNAL ILIAC ARTERY. 621 



In the foetus the internal iliac artery (hypogastric] is twice as large as the 

 external iliac, and appears to be the continuation of the common iliac. Instead 

 of dipping into the pelvis, it passes forward to the bladder, and ascends along 

 the sides of that viscus to its summit, to which it gives branches; it then passes 

 upward along the back part of the anterior wall of the abdomen to the umbilicus, 

 converging toward its fellow of the opposite side. Having passed through the 

 umbilical opening, the two arteries twine round the umbilical vein, forming with 

 it the umbilical cord, and ultimately ramify in the placenta. The portion of the 

 1 within the abdomen is called the hypogastric artery, and that external to 

 that cavity, the umbilical artery. 



At birth, when the placental circulation ceases, the upper portion of the 

 hypogastric artery, extending from the summit of the bladder to the umbilicus, 

 contracts, and ultimatelv dwindles to a solid fibrous cord ; but the lower portion, 

 extending from its origin (in what is now the internal iliac artery) for about an 

 inch and a half to the wall of the bladder, and thence to the summit of that organ, 

 is not totally impervious, though it becomes considerably reduced in size, and 

 serves to convey blood to the bladder under the name of the superior vesical 

 artery. 



Peculiarities as regards Length. In two-thirds of a large number of cases the length of 

 the internal iliac varied between an inch and an inch and a half: in the remaining third it 

 was more frequently longer than shorter, the maximum length being three inches, the minimum 

 half an inch. 



The lengths of the common and internal iliac arteries bear an inverse proportion to 

 each other, the internal iliac artery being long when the common iliac is short, and vice 

 r< />;. 



As regards its Place of Division. The place of division of the internal iliac varies 

 between the upper margin of the sacrum and the upper border of the sacro-sciatic for- 

 amen. 



The arteries of the two sides in a series of cases often differed in length, but neither seemed 

 constantly to exceed the other. 



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

 require 1 in case? of aneurism or haemorrhage affecting one of its branches. The vessel may be 

 secured by making an incision through the abdominal parietes in the iliac region in a direction 

 and to an extent similar to that for securing the common iliac : the transversalis fascia having 

 been cautiously divided, and the peritoneum pushed inward from the iliac fossa toward the 

 pelvis, the finger may feel the pulsation of the external iliac at the bottom of the wound, and by 

 tracing this vessel upward the internal iliac is arrived at, opposite the sacro-iliac articulation. It 

 should be remembered that the vein lies behind and on the right side, a little external to 

 the artery, and in close contact with it : the ureter and peritoneum, which lie in front, must also 

 be avoided. The degree of facility in applying a ligature to this vessel will mainly depend upon 

 its length. It has been seen that in the great majority of the cases examined the artery was 

 short, varying from an inch to an inch and a half; in these cases the artery is deeply seated in 

 tbe pelvis: when, on the contrary, the vessel is longer, it is found partly above that cavity. If 

 the artery is very short, as occasionally happens, it would be preferable to apply a ligature to the 

 common iliac or upon the external and internal iliacs at their origin. 



Probably a better method of tying the internal iliac artery is by an abdominal section in the 

 median line and reaching the vessel through the peritoneal cavity. This plan has been 

 advocated by Dennis of New York on the following grounds : (1 ) It no way increases the danger 

 of the operation : -' it prevents a series of accidents which have occurred during ligature of the 

 artery by the older methods; (3) it enables the surgeon to ascertain the exact extent of disease 

 in the main arterial trunk, and select his spot for the application of the ligature ; and (4) it 

 occupies much less time. 



Collateral Circulation. In Professor Owen's dissection of a case in which the internal 

 iliac artery had been tied by Stevens ten years before death for aneurism of the sciatic artery, 

 the internal iliac was found impervious for about an inch above the point where the ligature had 

 been applied, but the obliteration did not extend to the origin of the external iliac, as the ilio- 

 lumbar artery arose just above this point. Below the point of obliteration the artery resumed 

 its natural diameter, and continued so for half an inch, the obturator, lateral sacral, and gluteal 

 arising in succession from the latter portion. The obturator artery was entirely obliterated. 

 The lateral sacral artery was as large as a crow's quill, and had a very free anastomosis with the 

 artery of the opposite side and with the middle sacral artery. The sciatic artery was entirely 

 obliterated as far as its point of connection with the aneurismal tumor, but on the distal side of 

 the sac it was continued down along the back of the thigh nearly as large in size as the femoral, 

 being pervious about an inch below the sac by receiving an anastomosing vessel from the pro- 

 funda. 1 The circulation was carried on by the anastomoses of the uterine and ovarian arteries; 



1 Jfedico-Chirurgical Trans., vol. xvi. 



