614 THE BLOOD-VASCULAR SYSTEM 



(c) The deep artery of the penis or chtoris [a. profunda penis or clitoridis], larger in the male 

 sex, pierces the inferior laj'er of the urogenital diaphragm near the inferior ramus of the pubis. 

 It enters the crus of the penis (fig. 494) or clitoris, and is distributed in the corpus cavernosum 

 urethrse. 



(d) The dorsal artery of the penis or clitoris [a. dorsalis penis or clitoridis] (figs. 492, 494), 

 perforates the inferior fascia of the urogenital diaphragm near its apex. The dorsal nerve is 

 lateral to the artery and both join the dorsal vein (which lies between the arteries of either side) 

 on the dorsum of the penis or clitoris. The artery is much larger in the male than the female; 

 in either sex it supplies the glans, corona, and prepuce and anastomoses with the external 

 pudendal artery. 



THE EXTERNAL ILIAC ARTERY 



The external iliac artery [a. iliaca externa] — the larger in the adult of the two 

 vessels into which the common iliac divides opposite the lumbo-sacral articulation 

 — extends along the superior aperture of the pelvis, lying upon the medial border 

 of the psoas muscle, to the lower margin of the inguinal ligament, where, midway 

 between the anterior superior spine of the ilium and the symphysis pubis, it passes 

 into the thigh, and takes the name of the femoral. 



It measures 8.5 to 10 cm. (31 to 4 in.) in length. The course of the vessel is 

 indicated by a line drawn from 2.5 cm. (1 in.) below and a little to the left of the 

 umbilicus to a spot midway between the symphysis pubis and the anterior 

 superior spine of the ilium. If this line is divided into thirds, the lower two-thirds 

 indicate the situation of the external iliac, the upper third the common iliac. The 

 external iliac vein, the continuation upward of the femoral vein from the thigh, 

 lies to the medial side of the artery, but on a slightly lower plane, and, just before 

 its termination, gets a little behind the artery on the right side. 



Relations. — In front, the artery together with the vein is covered by the parietal per- 

 itoneum descending from the abdomen into the pelvis, and by a layer of condensed subperitoneal 

 tissue (Abernethy's fascia). It is crossed by the termination of the ileum on the right side, and 

 by the sigmoid colon on the left. The external spermatic (genital) branch of the genito- 

 femoral (genito-crural) nerve runs obliquely over its lower third, and just before its termination 

 it is crossed transversely by the deep circumflex iliac vein. The internal spermatic or ovarian 

 vessels lie for a short distance on the lower part of the artery, and the ductus deferens in the male 

 curves over it to descend to the pelvis. It is sometimes crossed at its origin by the ureter. The 

 external iliac lymphatic nodes lie along the course of the artery. The commencement of its 

 inferior epigastric branch is also in front. 



Behind. — At first the artery lies partly upon its own vein; lower down upon the medial 

 border of the psoas; and just before it passes through the lacuna vasorum, beneath Poupart's 

 ligament, upon the tendon of the psoas. The continuation of the iliac into the endo-pelvic fascia 

 is also below it. 



To its medial side is the external iliac vein, the peritoneum, and the ductus deferens in the 

 male, or the ovarian vessels in' the female. 



To its lateral side is the psoas muscle and the iliac fascia. 



The collateral circulation is carried on (fig. 497) when the external iliac is tied, by the anas- 

 tomosis of the iUo-lumbar and lumbar arteries with the circumflex iliac; the internal mammary 

 with the inferior epigastric; the obturator with the medial circumflex; the inferior gluteal with 

 the medial circumflex and superior perforating; the gluteal with the lateral circumflex; the 

 arteria comitans nervi ischiadici from the inferior gluteal, with the perforating branches of the 

 profunda; the external pudenal with the internal pudendal; the pubic branch of the obturator 

 with the pubic branch of the epigastric. 



The branches of the external iliac artery are : — (1) The inferior epigastric; (2) 

 the deep circumflex iliac; and (3) several small and insignificant twigs to the 

 neighbouring psoas muscles and lymphatic gland. 



(1) The Inferior Epigastric Artery 



The inferior or deep epigastric artery [a. epigastrica inferior] (fig. 495) usually 

 comes off from the external iliac just above the inguinal ('Poupart's) ligament. 

 Immediately after its origin, the ductus deferens in the male, and the round 

 ligament in the female, loop around it on their way to the pelvis. It here lies 

 medial to the abdominal inguinal (internal abdominal) ring, behind the inguinal 

 canal, and a little abov(! and lateral tc the femoral ring. Thence it ascends with 

 a slightly medial direction passing above and to the lateral side of the subcu- 

 taneous inguinal (external abdominal) ring, lying between the fascia transversalis 

 and the peritoneum. Having i)i(!rced the fascia transversalis at this point, it 



