1456 



SUKFACE AND SUKGICAL ANATOMY. 



The sciatic nerve enters the buttock at a point corresponding to the junction of 

 the upper and -middle thirds of a line drawn from the superior posterior iliac 

 spine to the sciatic tuberosity; from this point the nerve passes downwards and 

 slightly laterally upon the ischium to a point midway between its sciatic tuber- 

 osity and the greater trochanter. The spine of the ischium and the pudendal 

 vessels are situated opposite the junction of the lower and middle thirds of the 

 above line. The vessels and nerves which enter the buttock through the greater 

 sciatic foramen below the piriformis, may be exposed through an incision below 

 and parallel to that above described for exposing the superior gluteal artery, viz., 

 an incision corresponding to the middle two-fourths of a line extending from the 

 upper end of the gluteal cleft to the root of the greater trochanter ; the deep land- 

 marks are the lower border of the piriformis and the root of the sciatic spine. 



THE BACK OF THE THIGH. 



The hamstring muscles, and especially the tendon of the biceps and semi- 

 tendinosus, are thrown into prominence either by standing on tiptoes with the 

 knees slightly flexed, or by flexing the leg against resistance. By throwing the 



Femur 



Vastus intermedius 



Rectus femoris 



Vastus medialis 



Nerve to vastus medialis 

 Saplienous nerve 

 Sartorius 



Femoral vein 



Femoral artery 



Adductor longus 



Great saphenous vein 



Gracilis 



Vastus lateralis 



Lateral intermuscular septum 



Sciatic nerve 



Adductor magnus 

 Profunda femoris artery 



Semitendinosus 



Biceps | Semimembranosus 



Adductor brevis 



FIG. 1118. SECTION THROUGH THIGH AT THE LEVEL OF THE PROXIMAL PART OF THE ADDUCTOR CANAL. J 



hamstrings into action, the line of the lateral intermuscular septum of the thigh is 

 indicated by a well-marked furrow, extending from the lower edge of the insertion 

 of the glutseus maximus to the lateral aspect of the knee; behind this furrow is the 

 biceps femoris, and in front of it is the large vastus lateralis, covered by the" 

 strong ilio-tibial tract of the fascia lata. The shaft of the femur may be cut 

 down upon along the whole length of this furrow with least injury to the soft parts ; 

 the popliteal surface of the femur and deep-seated popliteal abscesses are most 

 conveniently reached through the lower part of the same incision. 



The course of the sciatic nerve corresponds to the proximal half of a line 



