360 



THE MUSCLES 



shaped flesliy exi)ansio)i, Avhich ends in sliort tendinous fibres blending with those 

 of the adductor longus and adchictor niagnus. 



Nerve-supply. — From tlie third and fourth nerves of the luml)ar })lexus by the 

 sujierficial branch of the obturator nerve, -which sends filaments to the anterior 

 surface of the muscle near the lower part of its upper border. Sometimes, how- 

 ever, it derives its nerve-supply from the deeper division of the obturator nerve, and 

 in tliat case the nerves enter the muscle from behind. 



Fig. 290. — The Deep Muscles of the Back of the Thigh. 



Gluteus minimus 



Obturator extemus 



Gluteus mazimus — -, — 



Vastus extemus 



Short head of biceps 



Tendon of biceps 



Obturator internus 



Adductor magnus 



Vastus internus 



Action. — Like the preceding, it is an adductor and rotator outwards of the 

 femur, ])ut it will not assist so powerfully in flexion. 



Relations. — In front, the pectineus, adductor longus, the profunda vessels, and 

 sujierficial l>ranch of the oljturator nerve; behind, the obturator externusand 

 adductor magnus, and the deep brancli of tlie ol>turator nerve. 



Variations.— It is sometimes divideil intij an upper and a lower portion. Occasiunully it 

 joins above with tlie oljturator externus. 



