THE LOWER EXTREMITY, POSTERIOR. 621 



(covered by the aponeurosis derived from the tendon of the 

 semimembranosus muscle). The contents of this space, are : 

 The popliteal artery, vein, nerves, and their branches ; the 

 small sciatic and terminal branch of the obturator nerves ; 

 the external or short saphenous vein ; lymphatic glands, 

 and adipose tissue. 



The relations of the artery, vein and nerves. The popli- 

 teal nerves are the most superficial, the external running 

 along the inner edge of the tendon of the biceps muscle, 

 the internal descending vertically through the space. The 

 vein is deeper than the nerve and slightly internal to 

 it (in the upper part of the space). The artery is still 

 deeper than the vein (in close union with it) and a little to 

 its inner side (in the upper half of the space). 



DISSECTION. 



Divide the two branches that go to form the external saphenous nerve, and 

 the inner and outer head of the gastrocnemius just above their junction. 



Turn the lower part of the muscle downward and separate the upper heads, 

 saving their nerve supply. Clean the parts presenting 



Plantaris. Figs. 128, 129, 131. 



Origin. From the lower part of the external bifurcation 

 of the linea aspera, the posterior surface of the femur ad- 

 jacent thereto, and from the posterior ligament of the knee 

 joint. 



Insertion. By a long slender tendon which descends 

 between the gastrocnemius and the soleus to be attached 

 into the os calcis at the inner side of the tendo-Achillis. 



Nerve Supply. The internal popliteal. 



Action. A feeble flexor of the leg upon the thigh, and 

 extensor of the foot upon the leg. 



Popliteus. Fig. 130. 



Origin. From the anterior portion of the transverse 



