GASTROCXEMIUS MUSCLE. 



283 



Soemmerring), form the bulk of the calf of the leg, and are inserted into 

 the heel by a common tendon the tendo Achillis ; the third, a small muscle, 

 the plantariSj descends between the other two. 



The gastrocnemius muscle arises by two thick tendinous heads from 

 the condyles of the femur, and ends below in the tendo Achillis. The 



Fig. 215. SUPERFICIAL MUSCLES OP THE LEG, SEEN 

 PROM BEHIND (after Bourgery). 



1, lower part of the vastus externus ; 2, tendon of 

 the biceps flexor cruris, passing to its insertion in the 

 fibula ; 3, lower part and tendon of the semitendinosus ; 

 4, lower part of the semimembranosus : its tendon is 

 seen between 3 and 5 passing to its insertion in the 

 tibia ; 5, gracilis ; 6, small part of the sartorius ; 7, 

 outer, and 8, inner head of the gastrocnernius on the 

 tendinous .part of the calf of the leg ; 9, placed in the 

 popliteal space, points to the muscular part of the 

 plantaris ; 9', its thin tendon inside the tendo 

 Achillis ; 10, the fibres of the soleus descending to 

 the flat tendon, which, joining with that of the gastro- 

 cnemius, forms + + the tendo Achillis ; 11, lower part 

 and tendon of the peroneus longus ; 12, lower fibres 

 of the peroneus brevis, both passing behind the mal- 

 leolus externus below ; 13, lower part of the flexor 

 longus digitorum ; 14, small part of the tendon of 

 the tibialis posticus, which, alotig with 13, descends 

 behind the malleolus internus ; 15, is placed near the 

 lower part of the fibula, and points to the lower 

 fibres of the flexor longus pollicis, the tendon of 

 which is seen descending over the tibia at 15'. 



outer tendon of origin is attached in an 



oblique line to a depression on the outer side 



of the external condyle, above the groove for 



the popliteus muscle. The inner tendon is 



attached in a horizontal line to an impression 



above the back part of the internal condyle, 



and along with it are fleshy fibres connected 



for a short distance with the ridge running 



to the linea aspera. The muscular fibres 



descending from the two heads remain 



separated by a vertical groove on the surface, 



but those next the middle meet at an angle 



on a tendinous structure below. The fibres 



of the superior tendons spread out upon the 



surface of the muscle ; the inferior tendon 



lies on the deep surface of the muscular mass, 



and is continued upwards in a thin aponeu- 



rosis with parallel fibres, which glide against 



the soleus : between the superficial tendon of 



each head and the deep common tendon, the 



greater number of the muscular fibres run 



obliquely downwards and forwards. The 



lower edge of each muscular part presents a convexity downwards; the inner 



descending furthest. A synovial membrane, usually communicating with 



the knee-joint, lies beneath the inner head of origin, and separates it from 



