The Popliteal Space. 345 



the articular branch of the obturator nerve lies on the 

 artery. On the outer side of the space, under cover of 

 the biceps tendon, is the external popliteal nerve, while, on 

 either side, among the tendons are the different popliteal 

 bursse. The biceps muscle, forming part of the outer 

 boundary, is readily recognized beneath the skin, by the 

 finger; whereas, on the inner side, the muscular bulk is 

 composed, superficially, of the semi-tendinosus, the long 

 rounded tendon of which may be felt, as a rounded cord, 

 running downwards and inwards, and of the semi-mem- 

 branosus, which lies beneath and is broader than the semi- 

 tendiosus and which may be felt projecting about half an 

 inch on either side of the latter tendon, while, most inter- 

 nal of all is the gracilis. The internal popliteal nerve 

 passes through the middle of the popliteal space and is 

 termed the posterior tibial at the lower extremity of the 

 space. It is separated by areolar tissue from, and lies to 

 the outer side of the vessels above the level of the knee 

 joint, but, below this, it is in close relation with them, and 

 gradually crosses them, so that, at the lower end of the 

 space, it lies internal to the vessels. This nerve sends 

 articular branches, which accompany the internal articular 

 and the azygos articular arteries ; muscular, which sup- 

 ply the gastrocnemius, plantaris, soleus and popliteus, 

 and, lastly, a branch which forms, with the corresponding 

 branch from the external popliteal, the short saphenous 

 nerve which accompanies the short saphenous vein. The 

 external popliteal nerve lies parallel with and slightly be- 

 hind the inner border of the biceps muscle. As it de- 

 scends it diverges from the middle line and is best recog- 

 nized by the finger on a level with the most prominent part 

 of the posterior surface of the internal condyle. Above 

 this point, it is possible to identify it by the sensation im- 

 parted when the nerve is pressed upon, but, below this, 



