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ANATOMY AND PHYSIOLOGY 



CALF MUSCLES (Fics. 93, 97) 



Triceps surse, and plantaris. 



The gastrocnemius. Origin. By two heads just above the 

 condyles of the femur. Insertion. On the calcaneus. 



Note. The two heads form the 

 lower boundaries of the popliteal 

 space. 



The soleus is covered by the gas- 

 trocnemius. Origin. Medial border 

 . of the tibia and lateral border of the 

 fibula. Insertion. The os calcis, 

 with the above muscle. 



Action of the two. They join to 

 form one muscle, the triceps surse (or 

 triceps of the calf), which has the 

 strongest tendon in the body, the tendo 

 calcaneus (tendon of Achilles} by 

 which they are attached to the os 

 calcis, and, therefore, they lift the heel. 

 If the muscles of both legs act at the 

 same time, the whole body is lifted on 

 the toes. 



Nerve to both. Tibial. 



The plantaris. Origin. With the outer 

 head of the gastrocnemius. Insertion. 

 With the tendo calcaneus. 



Note. The belly is short and small; the 

 tendon is the longest in the body. 



The calf muscles constitute a group 

 of great power, as by them one lifts 

 oneself to stand upon the toes. 



The sole of the foot, or plantar 

 region, resembles the palm of the 

 hand in having special groups of mus- 

 cles for the great and little toes, with the long flexor tendons 

 lying between them, and a dense fascia covering them. This is 

 called the plantar fascia. 



The nerves are medial and lateral plantar. 



FIG. 97. LATERAL ASPECT AND 

 CALF OP LEG. 



J 2, 3, 4, Lateral view, mus- 

 cles passing in front of ankle; 5, 

 6, peroneus brevis and p. lon- 

 gus (behind ankle); 7, 8, soleus 

 and gastrocnemius; 9, head of 

 fibula; 10, biceps femoris; u, 

 semimembranosus; 13, tendo 

 Achillis; 15, annular ligament; 

 16, 17, insertions of peroneus 

 tertius and brevis; 18, short ex- 

 tensor of toes; 19, plantar mus- 

 cle; 20, patella. (Sappey.) 



