MYOLOGY. 73 



great or internal cuneiform bone, as also into the base of the great toe. 

 Use : to flex the ankle, to adduct the foot, to turn the toes inwards, and to 

 support the leg when standing. 



Extensor digitonmi longus arises from the external part of the head of the 

 tibia, and from the upper part of the fibula, and is inserted by four tendons 

 into the back of the last phalanx of each toe (except the great toe). Use : 

 to extend the toes and flex the ankle. 



Extensor pollicis proprius arises from the inner edge of the middle third 

 of the fibula, and is inserted by two tendinous fasciculi, one into the base of 

 the first phalanx, and the other into the base of the second or last phalanx 

 of the great toe. Use : to extend the great toe and flex the ankle. 



Peronceus tertius or anticus arises from the anterior surface of the lower 

 half of the fibula, and is inserted into the base of the fifth metatarsal bone. 

 Use: to extend the little toe, to flex the ankle, and to raise the outer edge 

 of the foot. 



Peroyiaus longus arises from the head of the fibula and from the adjacent 

 surface of the tibia ; it is inserted into the outer side of the metatarsal bone 

 of the great toe and into the adjacant sesamoid bone. Use : to extend the 

 ankle joint, to press the great toe against the ground as in walking, and to 

 turn the foot outwards. 



Peronoepbs brevis arises from the lower half of the fibula, and is inserted 

 into the base of the metatarsal bone of the little toe and into the os cuboi- 

 des. It is similar to the last in its uses. 



5. Muscles of the back part of the Leg. These are seven in num- 

 ber, arranged in a superficial and a deep layer ; the former consists of the 

 gastrocnemius, soielus, and plantaris ; the latter, of the tibialis posticus, 

 flexor pollicis longus, flexor digitorum communis, and poplitasus. 



Gastrocnemius arises by two heads, one from a digital depression on the 

 upper and back part of the internal condyle of tlie femur, the other from 

 above the external condyle. The two fleshy bellies form the calf of the 

 leg, these ending in a broad flat tendon about the middle of the limb, which 

 with the tendon of the subjacent soloeus is inserted into the lower and back 

 part of the os calcis, as the tendo achillis. Use : to extend the ankle joint, 

 and to throw the whole weight of the body forward on the toes, as in pro- 

 gression. 



Plantaris arises from the back part of the femur, above the external con- 

 dyle and from the posterior ligament, of the knee ; it is inserted into the os 

 calcis a little anterior to the tendo achillis. Use : to extend the foot and 

 turn it inwards ; also to flex the knee. 



Solceus arises from the back part of the tibia and fibula by two slightly 

 developed heads, and is inserted into the os calcis by the tendo achillis, 

 common to it and the gastrocnemius. It assists in extending the ankle, but 

 can exert no influence on the knee joint. 



Poplitoius arises from a depression on the external surface of the outer 

 condyle, and is inserted into a flat triangular surface which occupies the 

 superior fifth of the posterior surface of the tibia. Use : to bend the knee, 

 and when bent to twist the foot inwards. 



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