POSTERIOR TIBIO-FIBULAR REGION. 



343 





POSTERIOR TIBIO-FIBULAR REGION. 



Dissection (fig. 189). Make a vertical incision along the middle line of the back of the leg, 

 from the lower part of the popliteal space to the heel, connecting it below by a transverse incision 

 extending between the two malleoli; the flaps of integument being removed, the fascia and muscles 

 should be examined. 



The muscles in this region of the leg are subdivided into two layers, superficial 

 and deep. The superficial layer constitutes a powerful muscular mass, forming 

 what is called 'the calf of the leg. Its 



large size is one of the most characteristic Fi s- 192. Muscles of the Back of the Leg. 

 features of the muscular apparatus in 

 man, and bears a direct connection with 

 his ordinary attitude and mode of pro- 

 gression. 



/Superficial Layer. 



Gastrocnemius. Soleus. 



Plantaris. 



The Gastrocnemius is the most super- 

 ficial muscle, and forms the greater part 

 of the calf. It arises by two heads, which 

 are connected to the condyles of the femur 

 by two strong flat tendons. The inner 

 head, the larger, and a little the most 

 posterior, is attached to a depression at 

 the upper and back part of the inner 

 condyle; the outer head, to the upper 

 and back part of the external condyle, 

 immediately above the origin of the 

 Popliteus. Both heads, also, arise by a 

 few tendinous and fleshy fibres from the 

 ridges which are continued upwards from 

 the condyles to the linea aspera. Each 

 tendon spreads into an aponeurosis, which. 

 covers the posterior surface of that por- 

 tion of the muscle to which it belongs ; 

 that covering the inner head being longer 

 and thicker than the outer. From the 

 anterior surface of these tendinous ex- 

 pansions, muscular fibres are given off'; 

 those in the median line, which cor- 

 respond to the accessory portions of the 

 muscle derived from the bifurcations of 

 the linea aspera, unite at an angle upon 

 a median tendinous raphe below. The 

 remaining fibres converge to the posterior 

 surface of an aponeurosis which covers 

 the front of the muscle, and this, gradu- 

 ally contracting, unites with the tendon 

 of the Soleus, and forms with it the tendo 

 Achillis. 



Relations. By its superficial surface, 

 with the fascia of the leg, which sepa- 

 rates it from the external saphenous vein 

 and nerve. By its deep surface, with the 



Tendon* of 



NW LBNCU * IIUII 



