THE HYPOGASTRIC ARTERY 



617 



with the corresponding vessel of the opposite side, and with the inferior epigastric 

 artery. 



Outside the pelvis, the obturator artery divides at the upper margin of the obtur- 

 ator foramen, into an anterior and a posterior branch which encircle the foramen 

 under cover of the Obturator externus. 



The anterior branch runs forward on the outer surface of the obturator mem- 

 brane and then curves downward along the anterior margin of the foramen. It 

 distributes branches to the Obturator externus, Pectineus, Adductores, and Gracilis, 

 and anastomoses with the posterior branch and with the medial femoral circum- 

 flex artery. 



The posterior branch follows the posterior margin of the foramen and turns for- 

 ward on the inferior ramus of the ischium, where it anastomoses with the anterior 

 branch. It gives twigs to the muscles attached to the ischial tuberosity and anas- 

 tomoses with the inferior gluteal. It also supplies an articular branch which 

 enters the hip-joint through the acetabular notch, ramifies in the fat at the bottom 

 of the acetabulum* and sends a twig along the ligamentum teres to the head of the 

 femur. 



Peculiarities. The obturator artery sometimes arises from the main stem or from the posterior 

 trunk of the hypogastric, or it may spring from the superior gluteal artery; occasionally it arises 

 from the external iliac. In about two out of every seven cases it springs from the inferior epi- 

 gastric and 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 lateral side of the 

 femoral ring (Fig. 541 A) ; in such cases it would not be endangered in the operation for strangulated 

 femoral hernia. Occasionally, however, it curves along the free margin of the lacunar ligament 

 (Fig. 54 IB), and if in such circumstances a femoral hernia occurred, the vessel 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. 



FIG. 541. Variations in origin and course of obturator artery. 



The internal pudendal artery (a. pudenda internet,; internal pudic artery) is the 

 smaller of the two terminal branches of the anterior trunk of the hypogastric, and 

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

 the same in the two sexes, the vessel is smaller in the female than in the male, and 

 the distribution of its branches somewhat different. The description of its arrange- 

 ment in the male will first be given, and subsequently the differences which it 

 presents in the female w r ill be mentioned. 



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

 lower border of the greater sciatic foramen, and emerges from the pelvis between 

 the Piriformis and Coccygeus; it then crosses the ischial spine, and enters the peri- 

 neum through the lesser sciatic foramen. The artery now crosses the Obturator 

 internus, along the lateral wall of the ischiorectal fossa, being situated about 4 cm. 

 above the lower margin of the ischial tuberosity. It gradually approaches the 

 margin of the inferior ramus of the ischium and passes forward between the two 

 layers of the fascia of the urogenital diaphragm; it then runs forward along the 

 medial margin of the inferior ramus of the pubis, and about 1.25 cm. behind the 

 pubic arcuate ligament it pierces the inferior fascia of the urogenital diaphragm 

 and divides into the dorsal and deep arteries of the penis. 





