The Posterior Limb 223 



by the great saphenous artery and vein and the greater saphenous 

 nerve. 



The sartorius and gracilis should be raised from the surface and 

 divided. 



(c) The biceps f emoris : Qrigin in two portions : 



First portion (caput breve) : Spinous processes of three 

 posterior sacral and three anterior caudal vertebrae. This 

 portion is triangular in shape, the distal end, or apex of the 

 triangle, passing into a thin fiat tendon which is inserted on 

 the lateral margin of the patella. 



Second portion (caput longum): Dorsal surface of the 

 ischial tuberosity, fused with the adductor magnus,.and the 

 lateral process, fused with the second, or deep portion of 

 the semimembranosus. This portion is also triangular, the 

 base being distal and providing a broad insertion on "the 

 fascia of the proximal third of the lateral surface of the 

 leg. The first, or superficial head of the semimembranosus, 

 covers this portion at its origin, which is also crossed by the 

 sciatic vein. 



To free the biceps and divide it: Incision along the apon- 

 eurotic line joining the tip of the great trochanter with the 

 sacrum; also distad along the intermuscular septum of the 

 lateral surface of the thigh from the great trochanter to the 

 knee. An incision along the first portion of the sciatic 

 vein will free the superficial head of the semimembranosus 

 from the biceps. Raise the biceps slightly by working the 

 handle of the scalpel under its distal portion. Divide the 

 muscle from its posterior margin, being careful not to injure 

 the slender tensor fasciae cruris muscle and the branches of 

 the sciatic nerve which lie beneath it. The first head of the 

 biceps may be separated and reflected in order to expose the 

 short muscles of the thigh. 



(d) The tensor fasciae cruris. Origin: By a long, slender 

 tendon, from the transverse process of the fourth sacral 

 vertebra. Insertion : Lateral fascia of the leg. This slender 

 muscular slip underlies the biceps femoris. 



