622 A MANUAL OF ANATOMY. 



groove near the lower margin of the external condyle of 

 the femur, from the posterior ligament of the knee joint. 



Insertion. Into the triangular surface of the tibia above 

 the oblique line, and into the deep surface of the aponeurosis 

 which covers the muscle. 



Nerve Supply. The internal popliteal, which distributes 

 a branch to the anterior surface of the muscle. 



Action. To flex the leg upon the thigh ; in flexion it 

 will rotate the leg internally (pronation). 



When the leg is extended the tendon of the muscle crosses 

 the transverse groove upon the external condyle ; in flexion 

 the tendon lies in the groove. 



Soleus. Figs. 129, 131. 



Origin. From the posterior surface of the head of the 

 fibula and the upper third of the same, from the external 

 intermuscular septum, from the oblique line and from the 

 inner border of the tibia as low as the middle of the bone, 

 from a tendinous arch which joins the back of the tibia 

 and fibula, and covers the popliteal vessels and nerves. 



Insertion. By the tendo-Achillis, which it helps form, 

 into the lower part of the posterior surface of the os calcis. 



Nerve Supply. The internal popliteal. 



Action. To extend the foot, as in raising the body in 

 walking, etc. 



The Tendo-Achillis. Figs. 129, 131. 



This is the strongest tendon in the body. It is formed 

 by the junction of the tendons of the gastrocnemius and 

 soleus muscles, and is attached to the lower part of the 

 posterior surface of the os calcis. Its dimensions are length, 

 from the middle of the leg to the heel, three to five inches, 

 five-eighths of an inch wide, three-eighths of an inch 

 thick. 





