8i8 HUMAN ANATOMY. 



the penis (or clitoris), and still more laterally the deep external pudic branch of the common 

 femoral artery. On reaching the glans, it forms an anastomotic circle around the base of that 

 structure, uniting with its fellow of the opposite side. Throughout its course it gives branches to 

 the corpus cavernosum and the integument of the penis or the prepuce of the clitoris. 



Variations. — The occasional origin from the internal pudic of the inferior vesical, middle 

 hemorrhoidal, and uterine arteries has already been noted. The internal pudic, instead of 

 passing out of the pelvis by the great sacro-sciatic foramen, may be directed forward upon the 

 floor of the pelvis and pass out beneath the pubic symphysis to become the dorsal artery of the 

 penis. More frequently this course is taken by an accessory internal pudic which arises from 

 the pudic in cases where this vessel appears to arise from the hypogastric axis, a condition 

 which results in the early division of the common stem from which the sciatic and internal 

 pudic arteries normally arise. 



The artery of the bulb may arise opposite the ischial tuberosity and pass obliquely forward 

 and medially across the ischio-rectal fossa, and in some cases it passes at first directly across 

 towards the anus and then bends forward to reach the bulb. 



The dorsal artery of the penis or clitoris occasionally unites with its fellow of the opposite 

 side to form a single median artery, or the two arteries of opposite sides may be united by trans- 

 verse anastomoses. Sometimes a third vessel arises either directly from the anterior division 

 of the internal iliac or from the obturator, even when this vessel takes its origin from the deep 

 epigastric. 



Anastomoses of the Internal Iliac. — The internal iliac makes anastomoses 

 with branches of the abdominal aorta and of the external iliac, and with its fellow of 

 the opposite side, and it is through these connections that the collateral circulation 

 may be established. 



Of branches communicating with the abdominal aortic system there are the 

 hemorrhoidal branches which anastomose with the superior hemorrhoidal from the 

 inferior mesenteric, the uterine which anastomoses with the ovarian, and the lateral 

 sacrals which anastomose with the middle sacral. Communications with the system 

 of the external iliac are through the sciatic with branches of the profunda femoris, 

 through the ilio-lumbar and gluteal with the external and internal circumflex iliacs, 

 and through the obturator with the deep epigastric through the pubic branches. The 

 anastomoses across the middle line occur between the vesical, prostatic (vaginal), 

 obturator, and internal pudic branches. 



THE EXTERNAL ILIAC ARTERY. 



The external iliac artery (a. iliaca externa) (Figs. 724, 728) extends from the 

 bifurcation of the common iliac, opposite the sacro-iliac articulation, to a point beneath 

 Poupart's ligament midway between the anterior superior spine of the ilium and the 

 symphysis pubis. It there becomes the femoral artery. In the adult the external 

 iliac is usually larger than the internal and is directed more nearly in the line of the 

 common iliac, downward, forward, and outward along the brim of the true pelvis. 



Relations. — Anteriorly, the artery is covered by peritoneum and is enclosed, 

 together with the vein, in a moderately dense sheath derived from the subperitoneal 

 tissue and termed Abernethy' s fascia. By the peritoneum it is separated on the 

 right side from the terminal portion of the ileum and sometimes from the vermiform 

 appendix, and on the left from the sigmoid colon. Near its origin it is crossed by 

 the ovarian vessels in the female and sometimes by the ureter ; near its lower end it 

 is crossed obliquely by the genital branch of the genito-crural nerve and by the deep 

 epigastric vein. Some lymph-nodes are also found resting upon its anterior surface. 

 Posteriorlv, it rests upon the iliac fascia, which separates it from the psoas muscle , 

 medially, it is crossed near its lower end by the vas deferens in the male and the 

 round ligament of the uterus in the female, and is accompanied throughout its 

 course by the external iliac vein, which lies, however, on a slightly posterior plane. 

 Laterally, it is in relation to the genito-crural nerve. 



Branches. — In addition to some small twig^ to the psoas muscle and to the 

 neighboring lymphatic glands, the external iliac gives origin to ( i ) the deep epigastric 

 and (2) the deep circumflex iliac arteries. 



Variations. — The external iliac varies considerably in length, according to the level at 

 which the abdominal aorta and the common iliac bifurcate. Independently of this, however, 

 and especially in aged individuals, it is frequently longer than is necessary to reach in a direct 



