246 INFERIOR EXTREMITY 



limb a few minute branches from the posterior cutaneous nerve 

 of the thigh may be discovered; (2) towards the lateral side 

 of the thigh some twigs from the lateral cutaneous nerve of 

 the thigh may be detected; (3) lastly, towards the medial 

 aspect of the limb endeavour to find some offsets from the 

 medial cutaneous (O.T. internal cutaneous'] branch of the femoral 

 nerve and twigs of obturator nerve. 



Deep Fascia. On removing the superficial fascia the deep 

 fascia will be observed to be exceedingly thin. It must now 

 be turned aside, and in doing this be careful of the trunk of 

 the posterior cutaneous nerve of the thigh, which passes down, 

 in the middle line of the limb, immediately subjacent to the 

 fascia. 



Hamstring Muscles. The hamstring muscles are three in 

 number, viz. the biceps femoris, the semitendinosus, and the 

 semimembranosus. They stretch from the tuberosity of the 

 ischium to the proximal ends of the tibia and fibula. The 

 biceps femoris is recognised from its diverging laterally to form 

 the lateral and proximal boundary of the fossa poplitea. The 

 semitendinosus and semimembranosus extend distally on the 

 medial side of the posterior aspect of the thigh, the former 

 on the superficial aspect of the latter. 



In cleaning these muscles the dissector should proceed cautiously to 

 work, otherwise he will injure the arterial and nerve twigs which enter 

 them. The latter may be easily secured by pulling proximally the 

 proximal part of the sciatic nerve, and at the same time gently separating 

 the muscles with the fingers. 



M. Biceps Femoris (O.T. Biceps). The biceps femoris 

 arises by two heads a long, or ischial, and a short, or femoral, 

 and is inserted, chiefly, into the head of the fibula. The 

 long head arises from the ischium by a tendon which is 

 common to it and the semitendinosus (Fig. 74, p. 200). 

 This is implanted into the medial of the two impressions 

 which mark the upper part of the tuber ischiadicum. Some 

 fibres from the ligamentum sacro-tuberosum are continued 

 into it. The short head arises from the back of the 

 femur below the insertion of the glutaeus maximus, viz. 

 from the lateral lip of the linea aspera, from the proximal 

 half of the lateral supracondylar ridge, and from the lateral 

 intermuscular septum. Its parallel fibres run obliquely 

 distally and laterally, and join the anterior and medial surface 

 of the tendon of insertion. This tendon, on the lateral 



