676 THE VASCULAR SYSTEMS 



The internal branch (ramus anterior) curves downward along the inner margin 

 of the obturator foramen, lying beneath the Obturator externus muscle; it dis- 

 tributes branches to the Obturator externus, Pectineus, Adductors and Gracilis, 

 and anastomoses with the external branch, and with the internal circumflex artery. 



The external branch (ramus posterior) curves around the outer margin of the 

 obturator foramen, also lying beneath the Obturator externus muscle, to the space 

 between the Gemellus inferior and Quadratus femoris, where it divides into two 

 branches. One, the smaller, courses inward around the lower margin of the 

 foramen and anastomoses with the internal branch and with the internal circum- 

 flex; the other inclines outward in the groove below the acetabulum (a. acetabulis), 

 and supplies the muscles attached to the tuberosity of the ischium and anasto- 

 moses with the sciatic artery. It sends through the cotyloid ^ notch a branch to 

 the hip-joint, which ramifies on the round ligament as far as the head of the femur. 



Peculiarities (Fig. 475). The obturator artery sometimes arises from the main stem 01 

 from the posterior trunk of the internal iliac, from the deep epigastric (28 per cent.), or it may 

 arise from the external iliac (1.2 per cent.). 



.4 B 



FIG. 475. Variations in origin and course of the obturator artery. 



When the obturator artery arises at the front of the pelvis from the deep epigastric, it descends 

 almost vertically to the upper part of the obturator foramen. The artery in this course usually 

 lies in contact with the external iliac vein and on the outer side of the femoral ring (Fig. 475, A); 

 in such cases it would not be endangered in the operation for femoral hernia. Occasionally, 

 however, it curves inward along the free margin of Gimbernat's ligament (Fig. 475, B), and 

 under such circumstances would almost completely encircle the neck of the hernial sac, and 

 would be in great danger of being wounded if an operation were performed for strangulation. 



The internal pudic artery (a. pudenda internet) (Figs. 476 and 477) is the 

 smaller of the two terminal branches of the anterior trunk of the internal iliac, 

 and supplies the external organs of generation. Though the course of the artery 

 is the same in the two sexes, the vessel is much smaller in the female than in the 

 male, and the distribution of its branches somewhat different. The description of 

 its arrangement in the male will first be given, and subsequently the differences 

 which it presents in the female will be mentioned. 



The internal pudic artery in the male passes downward and outward to the 

 lower border of the great sacrosciatic foramen, and emerges from the pelvis be- 

 tween the Pyriformis and Coccygeus muscles; it then crosses the spine of the 

 ischium and enters the pelvis through the lesser sacrosciatic foramen. The 

 artery now crosses the Obturator internus muscle along the outer wall of the ischio- 

 rectal fossa, being situated about an inch and a half above the lower margin of 

 the ischial tuherositv. It gradually approaches the margin of the ramus of the 

 ischium. passes forward between the two layers of the triangular ligament of the 

 perineum; it then runs forward along the inner margin of the ramus of the pubis 

 and about half an inch behind the subpubic ligament it pierces the superficial 

 layer of the triangular ligament and divides into its two terminal branches, the 

 dorsal artery of the penis and the artery of the corpus cavernosum. 



