ABDOMINAL CAVITY 545 



vein to form the inferior vena cava. Each common iliac vein 

 is formed by the junction pf the external iliac vein and the 

 hypogastric vein. 



The common iliac vein of each side is joined by the ilio- 

 lumbar vein. The left common iliac vein also receives the 

 middle sacral vein. 



Arteria Iliaca Externa (External Iliac Artery). This vessel 

 is the first or abdominal portion of the great arterial trunk 

 which carries blood to the lower limb. It begins opposite 

 the sacro-iliac articulation, at the level of the lumbo-sacral 

 articulation, and extends obliquely downwards and laterally, 

 along the brim of the small pelvis, to the inguinal ligament, 

 behind which it passes into the thigh, and becomes \htfemoral 

 artery. Its course is indicated on the surface by the lower 

 two-thirds of a line drawn from a point a little below and to 

 the left side of the umbilicus to a point midway between the 

 symphysis pubis and the anterior superior spine of the ilium. 

 The upper third of the line indicates the position of the 

 common iliac artery. 



The external iliac, like the common iliac artery, is closely 

 covered by peritoneum. The right artery passes behind the 

 terminal part of the ileum, and the left behind the pelvic 

 colon. Towards its termination each external iliac artery is 

 crossed by the deep circumflex iliac vein, and the external 

 spermatic nerve (O.T. genital branch of genito-crural). In 

 the male this part of the artery is also crossed by the ductus 

 deferens and the internal spermatic vessels, and in the female 

 by the round ligament of the uterus. At first the external 

 iliac artery rests upon the medial margin of the psoas magnus 

 muscle, but close to the inguinal ligament it comes to lie 

 directly in front of that muscle. The artery is separated from 

 the muscle, however, by the iliac fascia, to which it is bound 

 down by a condensed part of the extra-peritoneal tissue, which 

 passes over it. The external spermatic nerve lies along the 

 lateral side of the artery, and the companion vein is placed 

 on its medial side ; on the right side, however, the vein, as it 

 passes upwards, gradually comes to lie behind the artery. 



The external iliac gives off two large branches to the 

 abdominal wall, viz. (i) the inferior epigastric; (2) the deep 

 circumflex iliac. They arise close to the inguinal ligament, and 

 have both been examined (pp. 404, 405). The veins corre- 

 sponding to these arteries open into the external iliac vein. 



VOL. i 35 



