ARTERIES OF THE PELVIC LIIIB 673 



through the greater sciatic foramen, dividing into several branches as it emerges; 

 these enter the gluteal muscles (Fig. 580). 



6. The iliaco-femoral or lateral circumflex artery of the thigh (A. circumflexa 

 femoris lateralis) passes ventro-laterally across and beneath the shaft of the ilium, 

 under cover of the iliacus muscle, and dips in between the rectus femoris and vastus 

 lateralis. It is accompanied by two satellite veins. It gives collateral branches to 

 the iliopsoas, the glutei, and the tensor fasciae latis, supplies the nutrient artery of 

 the ilium, and terminates in the quadriceps femoris (Fig. 580) . 



7. The obturator artery (A. obturatoria), the medial terminal branch of the 

 internal iliac, passes downward and backward on the pelvic surface of the shaft of 

 the ilium, along the ventral border of the iliac head of the obturator internus, ac- 

 companied by the satellite vein and nerve, which lie ventral to the artery (Fig. 576) . 

 On reaching the obturator foramen it dips under the obturator internus and passes 

 obliquely through the lateral part of the foramen. In this part of its course it 

 gives off a vesical branch and twigs to the obturator internus and the hip-joint. 

 It emerges from the obturator foramen behind the obturator externus, passes be- 

 tween the quadratus femoris and the adductor, runs backward on the ventral face 

 of the ischium, and, in the male, enters the crus penis, forming the arteria profunda 

 penis. It anastomoses with the internal pudic, and usually with the external 

 pudic by a branch (A. dorsalis penis caudalis) which runs forward on the dorsum 

 penis. Collateral branches are detached to the obturator muscles, the adductors 

 of the thigh, the semimembranosus, biceps femoris, and semitendinosus, and anas- 

 tomoses are formed with the deep femoral and posterior femoral arteries. In the 

 female the terminal part is small and enters the root of the clitoris. 



ARTERIES OF THE PELVIC LIMB 



The main arterial trunk of each pelvic limb descends to the proximal part of 

 the posterior surface of the tibia, where it divides under cover of the popliteus 

 muscle into the anterior and posterior tibial arteries. The different parts of the 

 trunk receive names which correspond to the several regions through which it 

 passes. In the abdomen it is termed the external iliac artery, in the proximal two- 

 thirds of the thigh it is called the femoral artery, and distal to this it is termed the 

 popliteal artery. 



The External Iliac Artery (Figs. 575, 576) 



The external iliac artery (A. iliaca externa) arises from the aorta under the 

 fifth lumbar vertebra, and usually just in front of the origin of the internal iliac. 

 It descends at the side of the pelvic inlet along the tendon of the psoas minor, 

 crosses the insertion of that muscle, and reaches the level of the anterior border of 

 the pubis, beyond which it is continued by the femoral artery. It is covered by the 

 peritoneum and fascia, and is related behind to the corresponding vein. Its chief 

 branches are as follows: 



1. The circumflex iliac artery (A. circumflexa ilium profunda) arises from the 

 external iliac at its origin or from the aorta directly. It passes across the iliac 

 fascia toward the tuber coxee, and divides into two branches at or near the lateral 

 border of the psoas minor. The artery lies between the fascia and the peritoneum 

 and is accompanied by two veins. It furnishes small branches to the psoas muscles 

 and the external iliac lymph glands. The anterior branch gives twigs to the iliacus 

 and psoas muscles, and passes downward and forward in the flank on the trans- 

 versus abdominis, along, or under cover of, the upper margin of the obliquus ab- 

 dominis internus. It gives branches to these muscles, the obliquus abdominis 

 externus, and the skin of the flank. The posterior branch perforates the abdominal 

 wall close to the tuber coxse, and runs downward on the medial face of the tensor 

 43 



