306 THE INFERIOR EXTREMITY 



subjects, indications of the outlines of the bellies of the 

 hamstring muscles may be seen. 



Dissection. Reflection of the Skin. Place a block under 

 the knee to support the limb and to render tense the muscles 

 which form the boundaries of the popliteal fossa. Incisions 

 (i) A vertical incision along the median line of the limb from 

 the junction of the middle and distal thirds of the thigh to the 

 junction of the proximal fourth with the distal three-fourths 

 of the leg. (2) A transverse incision at the proximal end of 

 the vertical incision. (3) A transverse incision at the distal 

 end of the vertical incision. Each of the two transverse 

 incisions should extend halfway round the limb. 



The two flaps of skin defined by the incisions (21 and 22, 

 Fig. 126) must be separated from the superficial fascia and turned 

 to their respective sides. 



Superficial Fascia Vena Saphena Parva (O.T. External 

 Saphenous Vein) Branches of the Posterior Cutaneous 

 Nerve of the Thigh (O.T. Small Sciatic). When the skin 

 is reflected the fatty layer of the superficial fascia of the 

 popliteal region is brought into view. It presents no peculiar 

 features, and, as a rule, it contains only a moderate amount 

 of fat, amidst which the following structures must be sought : 

 (i) The proximal part of the small saphenous vein-, (2) the 

 terminal part of the posterior cutaneous nerve of the thigh ; 



(3) branches of the posterior cutaneous nerve of the thigh ; 



(4) the posterior branch of the medial cutaneous nerve of 

 the thigh ; (5) the anastomotic peroneal nerve. 



Dissection. Look first for the small saphenous vein. It 

 ascends along the middle line of the back of the calf and pierces 

 the deep fascia over the distal part of the popliteal fossa. As 

 the proximal part of the vein is being cleaned secure the terminal 

 part of the posterior cutaneous nerve of the thigh which runs 

 alongside of the vein. At a higher level, in the fat in the middle 

 line of the proximal part of the popliteal area one or more twigs 

 from the posterior cutaneous nerve of the thigh may be found, 

 piercing the deep fascia on their way to the skin. 



When the medial side of the thigh was dissected the posterior 

 branch of the medial cutaneous nerve of the thigh was found 

 descending along the posterior border of the sartorius muscle 

 (Fig 127). It should be followed now as it descends behind the 

 medial boundary of the popliteal fossa to the back of the calf. 

 The peroneal anastomotic nerve may be found at the lower and 

 lateral part of the popliteal area as it pierces the deep fascia 

 covering the lateral head of the gastrocnemius muscle (Fig. 127). 

 In some cases, however, the nerve pierces the deep fascia at a 

 much more distal level. In such cases it will not be found until 

 the back of the leg is dissected. After the small saphenous 

 vein and the nerves* mentioned have been secured and cleaned, 

 remove the remains of the superficial fascia, but be careful to 

 avoid injury to the deep fascia which is somewhat thin. 



