190 



use with the 

 foot free, 

 and fixed ; 



acting from 

 below. 



Detach 



gastrocne- 



mius. 



Soleus is 

 attached to 

 the tones of 

 the leg, 



and joins 

 the tendon 

 below ; 



parts over 



and under 

 it; 



use, 



the foot 

 free, 

 and fixed ; 



acting from 

 below. 



Tendo 

 Achillis : 



extent, 



and inser- 

 tion. 



Plantaris : 

 origin ; 



insertion ; 



position of 

 the muscle ; 



DISSECTION OF THE LEG. 



outer. In the outer head a piece of nbro-cartilage or a sesamoid 

 bone may exist. 



Action. When the foot is unsupported, the gastrocneniius extends 

 the ankle ; and when the toes rest on the ground, it raises the os 

 calcis and the weight of the body, as in standing on the toes, and 

 in progression. 



Taking its fixed point at the os calcis, the muscle draws down the 

 femur so as to bend the knee-joint. 



Dissection. To see the soleus, the gastrocneniius is to be 

 reflected by cutting across the remaining head (fig. 72), and the 

 vessels and nerves it receives. After the muscle has been thrown 

 down, the soleus and plantaris must be cleaned. 



The SOLEUS (fig. 72, B) is a large flat muscle, which is attached 

 to both bones of the leg. It arises from the head, and the upper 

 third of the posterior surface of the shaft of the fibula ; from the 

 oblique line across the tibia, and from the inner edge of this bone 

 as low as the middle (fig. 73) ; and between the bones from an 

 aponeurotic arch over the large blood-vessels. Its fibres are directed 

 downwards to the common tendon. 



The superficial surface of the soleus is in contact with the gastro- 

 cneniius ; and where the two touch they are aponeurotic. Beneath 

 the soleus lie the bones of the leg, the deep muscles, and the vessels 

 and nerves. 



Action. In its action on the foot the soleus, like the gastro- 

 cneniius, extends the ankle and points the toes when the foot is 

 free to move, and raises the heel if the toes rest on the ground. 

 By the sudden and powerful contraction of the fibres of both muscles 

 the common tendon is sometimes broken across. 



If it acts from the os calcis, it will draw back the bones of the 

 leg into a vertical position over the foot, as the body is raised to the 

 erect posture after stooping. 



TENDO ACHILLIS (fig. 72, F). The common tendon of the gastro- 

 cneniius and soleus is one of the strongest in the body. About three 

 inches wide above, it commences at the middle of the leg, though 

 it receives fleshy fibres on its deep surface nearly to the lower 

 end : below, it is narrowed, and is inserted into the middle impression 

 on the posterior aspect of the tuberosity of the os calcis. A bursa 

 intervenes between it and the upper part of the tuberosity. The 

 tendon is close beneath the fascia ; and the external saphenous vein 

 and nerve are superficial to it at first, but afterwards lie along its 

 outer border. 



The PLANTARIS (fig. 72, c) is remarkable in having the longest 

 tendon in the body, which takes the appearance of a riband when 

 it is stretched laterally. About three-quarters of an inch wide, the 

 muscle arises from the line above the outer condyle of the femur, 

 and from the posterior ligament of the knee-joint ; and the tendon 

 is inserted into the os calcis with, or by the side of, the tendo 

 Achillis, or into the fascia of the leg. 



The belly of the muscle, about three inches in length, is concealed 

 by the gastrocnemius, but the tendon appears on the inner side of 



