THE INTERNAL ILIAC ARTERY 671 



Branches. The common iliac arteries give off small branches to the perito- 

 neum, Psoas magnus, ureters, and the surrounding cellular tissue, and occasionally 

 give origin to the iliolumbar or to the accessory renal arteries. 



Peculiarities. The paint of origin varies according to the bifurcation of the aorta. In 

 three-fourths of a large number of cases the aorta bifurcated either upon the fourth lumbar 

 vertebra or upon the intervertebral disk between it and the fifth, the bifurcation being, in one 

 case out of nine below, and in one out of eleven above, this point. In ten out of every thirteen 

 cases the vessel bifurcated within half an inch above or below the level of the crest of the ilium, 

 mnre frequently below than above. 



The point of division is subject to great variety. In two-thirds of a large number of cases 

 it was between the last lumbar vertebra and the upper border of the sacrum, being above that 

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

 divides lower do\vn more frequently than the right. 



The relative lengtiis, also, of the two common iliac arteries vary. The right common iliac 

 was the longer in sixty-three cases, the left in fifty-two, while 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 line between the highest points of the iliac crests: this is usually 

 half an inch below the umbilicus; in this line take a point halt" an inch to the left of the middle 

 line. From this draw two lines to points midway between the anterior superior spines nf the 

 ilium and the symphvsis pubis. These two diverging lines will represent the course of the 

 common and external iliac arteries. Draw a second line corresponding to the level of the ante- 

 rior superior spines of the ilium : the portion of the diverging Hues between these two levels will 

 represent the course of the common iliac arteryj the portion below the lower zone, that of the 

 external iliac artery. 



Applied Anatomy. The application of a ligature to the common iliac artery may be re- 

 quired on account of aneurism or hemorrhage implicating the external or internal iliacs. 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. The sheath is then 

 opened, and the needle passed from within outward. On the right side great care must be 

 exercised in passing the needle,, since both the common iliac veins lie behind the artery. After 

 the vessel has been tied the incision in the peritoneum over the artery should be sutured. In 

 amputation of the hip-joint the common iliac can be compressed most certainly and safely by 

 opening the abdomen and compressing the vessel by means of the fingers against the Psoas 

 muscle (McBurney's method). 



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 hemorrhoidal 

 branches of the internal iliac with the superior hemorroidal 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 

 iliolumbar 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. 



The Internal Iliac Artery (Figs. 467, 473). 



The internal iliac or hypogastric artery (a. hypogastrica} supplies the walls and 

 viscera of the pelvis, the buttock, the generative organs, and innpr sirip of thp 

 thigh. It is a short thick vessel, smaller in the adult than the external iliac, and 

 about an inch and a half in length. It arises at the bifurcation of the common 

 iliac, opposite the lumbosacral articulation, and, passing downward to the upper 

 .margin of the great sacrosciatic foramen, divides into two large trunks, an anterior 

 and a posterior. From its anterior division a partially impervious cord, a part of the 

 fetal hypogastric artery, extends forward to the bladder. 



Relations. In front, with the ureter, which is between the artery and the peritoneum. 

 Behind, with the internal iliac vein, the lumbosacral cord, and Pyritormis muscle. On its outer 

 ride, near its origin with the external iliac vein, which lies between it and the Psoas magnus 

 muscle; lower down, with the obturator nerve. 



