THIGH AND BUTTOCK. 



appears in the popliteal space on the vessels. It supplies (mus- 

 cular branches') the Obturator externus and the Adductor mag- 

 nus and (occasionally) brevis ; the terminal (articular) branch 

 runs through the posterior ligament to the knee-joint. [643] 



The superficial branch runs in front of the Obturator exter- 

 nus and Adductor brevis, under the Pectineus and Adductor 

 longus, and then descends along the inner border of the latter. 

 It divides into two terminal branches; one runs in Hunter's 

 canal to the femoral artery; the other (cutaneous branch) joins 

 branches of the internal cutaneous and internal saphenous 

 under the Sartorius, forming a plexus (obturator, or subsartorial 

 plexus), and may supply the lower two-thirds of the thigh in- 

 ternally. The other branches are: articular, to the hip- joint; 

 muscular, to the Adductor longus, Gracilis, Adductor brevis 

 (usually), and Pectineus (occasionally); and communicating 

 (inconstant), to the anterior crural. [644] 



Accessory Obturator (very inconstant). This arises from 

 the third, or third and fourth lumbar nerves, between the roots 

 of the obturator and anterior crural. Emerging from the inner 

 side of the Psoas and coursing over the pelvic brim behind the 

 external iliac vessels, it leaves the obturator nerve and runs 

 over the pubis to the thigh. It divides behind the femoral ves- 

 sels into three branches; one goes to the hip-joint, one replaces 

 the branch of the obturator to the Pectineus, and one commu- 

 nicates with the superficial branch of the obturator. More 

 rarely it may be more or less extensive. [647] 



Anterior Crural. Arising by three roots which unite in the 

 Psoas and emerge at its outer border, the nerve descends be- 

 tween the Psoas and Iliacus, and under Poupart's ligament ex- 

 ternal to the femoral sheath ; it splits up in Scarpa's triangle 

 into terminal branches. Muscular branches supply the Iliacus, 

 arising in the abdomen; Pectineus, running under the femoral 

 vessels; Sartorius, in two sets, to the upper and the middle 

 part; Vastus externus and Rectus femoris, to their deep sur- 

 faces; Crureus, superficially, the nerve running through it to 



[281] 



