REGION OF THE KNEE. 253 



mcnts of back of thigh. If the amputation be performed 

 near the knee, the muscles are liable to great contraction, 

 since they take their fixed points at the pelvis superiorly. 

 Hence the flaps, which should be lateral, external and 

 internal, must be cut as long as possible. The strong 

 fibrous sheaths of the muscles favor the bagging of pus 

 in amputations through the thigh. 



In cases of wounds of the thigh, in which either the 

 superficial or deep femoral is implicated, an approxima- 

 tive diagnosis of the site of the escape of blood may be 

 made by examining the posterior tibial artery at the 

 inner ankle. If it pulsates, in all probability the super- 

 ficial femoral is intact, and the profunda wounded ; on 

 the other hand, if the superficial femoral be the seat of 

 injury, the blood, instead of continuing its course along 

 it, and causing pulsation in the posterior tibial, is es- 

 caping into the surrounding tissues, and forming a false 

 aneurism. In enlarging the wound to find the bleeding 

 point, it must be remembered that the profunda is ex- 

 ternal to the superficial femoral, and that the veins of 

 either will be most likely involved. 



In fractures of the shaft of the femur, the lower frag- 

 ment is always drawn to the inner side of the upper one, 

 and rotated outwards, although in some instances in- 

 wards : in the former case, owing to the contraction of 

 the psoas and iliactis, and external rotators ; in the latter, 

 to the internal rotators. 



SURGICAL ANATOMY OF THE REGION OF THE 

 KNEE. 



This region is limited below by a line drawn round 

 the leg just below the internal tuberosity of the tibia ; it 

 will be thus seen that the popliteal space, which partly 



22 



