584 THE ARTERIES 



forating. The termination of tlie artery is sometimes called the fourth perforating 

 Ijranch. 



(a) The external circumflex, a short trunk, Init the largest in diameter of the 

 hranches of the artery, arises from the outer side of the profunda as it lies on the 

 iliacus muscle, about three-quarters of an inch (2 cm.) below the origin of that 

 vessel from the femoral. It passes transversely outwards over the iliacus, under 

 the sartorius and rectus, and between the branches of the anterior crural nerve. 

 In this course it gives off branches to the rectus and crureus, and then divides into 

 three chief sets of branches — an ascending, transverse, and descending. 



(i) The ascending branch, consisting of one or more separate vessels, runs 

 upwards beneath the sartorius; then, sinking deeply beneath the tensor fasciiu 

 femoris on the outer side, and the gluteus medius and minimus on the inner side, 

 anastomoses with the superior gluteal and the deep circumflex iliac arteries. This 

 branch also supplies a twig which runs upwards under the rectus to the hip-Joint. 



(ii) The transverse branch, or branches, run transversely outwards, and, 

 winding over the crureus and piercing the vastus externus, anastomose towards the 

 back of the thigh with the superior perforating liranch of the profunda, the sciatic, 

 and internal circuintlex arteries. These branches will usually be found a little 

 below the great trochanter. 



(iii) The descending branches run directly downwards along with the nerve 

 to the vastus externus muscle. They lie beneath the rectus muscle and on the 

 crureus or vastus externus, some of them being just under cover of the anterior 

 edge of the latter muscle. The}'^ are distributed to the vastus externus, crureus, 

 and rectus, one branch usually running along the anterior border of the vastus 

 externus as far as the knee-Jomt, where it anastomoses with the superior external 

 articular liranch of the popliteal (fig. 376); another, entering the crureus, anasto- 

 moses with the lower perforating branch of the profunda and Avith the anastomotica 

 magna. 



Variations of the external circumflex. — (A) It may come off from the femoral above tlie 

 profunda. (B) It may be double, one branch coiuinsr off from the femoral, and one from the 

 profunda, or botli from the profunda, or both from the femoral above the profunda. 



(h) The internal circumflex artery comes off from the back and inner part of 

 the profunda artery on al)()Ut tlie same level as the external circumflex; sometimes 

 as a common trunk with that vessel. As it winds round the inner side of the 

 femur to reach the region of the trochanters, it lies successively, first, Ijetween the 

 psoas and pectineus, then between the obturator externus and adductor brevis; 

 finally, between the adductor magnus and quadratus femoris, where it anastomoses 

 Avith the external circumflex externally, with the sciatic above, and with the 

 superior perforating below, forming the so-called crucial anastomosis. As it passes 

 between the obturator externus and adductor l)revis, it gives oft' two or more 

 branches to the adductor longus, the adductor ])revis, the gracilis, and the ol)turator 

 externus, and anastomoses with the oltturator artery. Another small liranch 

 usually courses upwards and outwards beneath the tendon of the psoas, and enters 

 the hip-joint beneath the transverse ligament, and, together Avith the articular In-anch 

 of the obturator, supplies the fatty tissue in the acetal)ulum, and sends branches to 

 the synovial membrane. As it lies beneath the adductor brevis, it gives off* a 

 descending branch to the adductor magnus and brevis. This branch is generally 

 accompanied by the posterior division of the ol)turator nerve. Before passing 

 betAveen the quadratus femoris and adductor magnus, a small l)ranch runs 

 upAvards Ijcneath the (juadratus femoris to sui)i)ly the back of the hip-joint, and 

 anastomoses Avith the gluteal and sciatic arti-ries. Its comi)anion veins join the 

 profunda vein. 



Variations of the internal circumflex. — (A) It may come off from the profunda artery before 

 tlie external eircumflex. (Bj It may arise from the femoral artery; or (C) from the external 

 iliac or one of its branches. 



(c) The perforating arteries of the profunda are so called because they per- 

 forate, in a more or less regular manner I'niiu above doAViiAvards. certain of the 



