SUPERFICIAL DISSECTIONS 23 



The Gastrocnemius (4). — The inner head of this muscle appears 

 from beneath the gracilis. The origin of this head from the supra- 

 condyloid crest is concealed by the muscle just mentioned. This portion 

 of the gastrocnemius has been displaced backwards in order to display 

 more fully the posterior tibial nerve, which emerges from beneath the 

 muscle. 



The Tendon of the Perforatus (14) will be observed to be placed 

 at first in front of that of the gastrocnemius. It then passes round the 

 inner aspect of the latter and becomes placed superficially to it, to 

 continue its course over the summit of the tuber calcis and down the 

 limb in the manner already described. 



The Popliteus (8). — This muscle arises from the lower and more 

 anterior of the two pits on the outer aspect of the external condyle 

 of the femur. Its origin is not displayed in the Plates represent- 

 ing the outer aspect of the limb, since it is concealed by the external 

 lateral ligament of the stifle, under which the tendon of the muscle 

 runs. 



The popliteus covers the posterior common ligament of the joint. 

 Its fibres take an oblique direction downwards and inwards, and are 

 inserted into the special tubercle on the postero-internal aspect of the 

 shaft, and the upper two-thirds of the inner edge, of the tibia. 



The greater portion of the muscle lies in the triangular, smooth, 

 depressed area with its apex directed downwards, which is found on 

 the back of the upper third of the tibia. This muscle is a flexor and 

 slight inward rotator of the stifle, and its nerve-supply is derived from 

 the internal popliteal nerve. 



The Flexor Accessorius (10). — Running obliquely downwards and 

 inwards, and placed in a groove along the line of apposition of the 

 popliteus and flexor perforans, is the flexor accessorius. The greater 

 portion of this muscle is visible, but its origin is concealed by the 

 gastrocnemius. It arises at the back of the external tuberosity of the 

 tibia. Its tendon of origin is succeeded by a somewhat flattened but 



