FOSSA POPLITEA 245 



ligament of the knee-joint. It pierces this ligament to reach 

 the synovial membrane. 



Vena Poplitea (Popliteal Vein). 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 fossa poplitea, 

 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. 



Nervus Obturatorius (Obturator Nerve). This minute 

 nerve will be found lying upon the medial side of the popliteal 

 artery. Trace it proximally and it will be seen to enter the 

 space by piercing the distal fibres of the adductor magnus ; 

 follow it distally, and it will be observed to enter the knee- 

 joint by penetrating 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 brought into view : 



1. Superficial fascia. 



2. Cutaneous nerves. 



3. Deep fascia. 



f Biceps femoris. 

 L Muscles J Semitendinosus. 



1CS ' 1 Semimembranosus. 

 V Adductor magnus. 

 -yr f Posterior cutaneous of thigh. 



' 6S ' \Sdatic. 

 6. Arteries, Four perforating. 



Reflection of Skin. A vertical incision must be made in the medial 

 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 Fascia Cutaneous Nerves. In the fatty super- 

 ficial fascia thus brought into view cutaneous twigs from four 

 sources must be looked for (i) along the medial line of the 

 i16 a 



