318 THE INFERIOR EXTREMITY 



middle genicular artery springs from the popliteal as it lies 

 upon the oblique popliteal ligament of the knee joint. It 

 pierces that ligament to reach the cruciate ligaments and the 

 synovial layer. 



Vena Poplitea. The popliteal vein is formed, near the 

 distal border of the popliteus muscle, by the union of the 

 venae comites of the anterior and posterior tibial arteries. 

 It runs proximally through the popliteal fossa, and, entering 

 the adductor canal, through the opening in the adductor 

 magnus, it becomes the femoral vein. The relations which 

 it presents to the popliteal artery have already been detailed. 

 In addition to tributaries corresponding to branches of the 

 artery, it receives the small saphenous vein, which has been 

 seen piercing the popliteal fascia to join it. By slitting it 

 open with the scissors the dissector will see that it possesses 

 three (sometimes four) valves in its interior. 



The Genicular Branch of the Obturator Nerve. This slender 

 continuation of the posterior division of the obturator nerve 

 usually lies upon the posterior aspect of the popliteal artery. 

 It enters the popliteal fossa by piercing the distal fibres of 

 the adductor magnus ; and it enters the knee joint after 

 passing through the oblique popliteal ligament. 



BACK OF THE THIGH. 



The dissection of the back of the thigh must be com- 

 pleted on the fifth day. The following are the structures 

 which are to be displayed : 



1. Superficial fascia. 



2. Cutaneous nerves. 



3. Deep fascia. 



/"Biceps femoris. 



Mnc^c J Semitendinosus. 



4. Muscles, 1 Semimembranosus> 



^Adductor magnus. 

 N /Posterior cutaneous of thigh. 



^_ oCltltlC. 



6. Arteries, Four perforating. 



Dissection. Reflection of Skin. A vertical incision must be 

 made, in the median line of the thigh, through the belt of skin 

 which still encircles the limb posteriorly. The two flaps can 

 then be reflected, the one laterally, and the other medially. 



Superficial Tascia Cutaneous Nerves. The superficial 



