MUSCLES OF THE LEG 



117 



MUSCLES OF THE LEG 



Posterior 



These muscles extend the ankle and flex the toes; they all pass 

 behind the medial malleolus. They are covered by the calf muscles. 



The tibialis posterior. Origin. Shaft of both tibia and fibula and the 

 interosseous membrane. Insertion. Navicular and first cuneiform bones. 



Action. Extension of the ankle. 



Nerve. Tibial. 



The long flexor of the great toe, or flexor hallucis lon- 

 gus. Origin. Shaft of fibula. Insertion. Last phalanx 

 of the great toe (Fig. 96). 



Nerve. Tibial. 



Long flexor of the toes, or flexor digitorum longus. 

 Origin. Shaft of fibula. Insertion. By four tendons 

 on the last phalanges of the four lateral toes (Fig. 96). 



Action of these two muscles. Flexion of the tips of 

 the toes. 



Nerve. Tibial. 



LEG LATERAL SIDE (FiG. 97) 



Peroneus brevis. Origin. Shaft of fibula. 

 Insertion. Base of fifth metatarsal bone. The 

 tendon passes behind the lateral malleolus. 



Peroneus longus. Origin. Shaft of fibula. 

 Insertion. In the sole of the foot, first cuneiform 

 and first metatarsal bones. The tendon passes DLE LAYER - 

 behind the lateral malleolus and crosses in the 

 sole to the medial border of the foot. '/ dividing into 



four tendons; 3, ten- 



Action of these two muscles. They extend don of long flexor of 

 the ankle and lift the lateral border of the foot. |7pi a nSr 4 muscles| 



9, projection of fifth 



Nerve to both. Superficial peroneal. metatarsal bone; 10, 



sheath of tendon of 



Note. As the tibialis anterior and pero- peroneus longus; n, 

 neus tertius flex the foot, so the tibialis pos- c 



FIG. 96. Mus- 

 REGION, MTD- 



terior and peroneus brevis extend it. 



Orthopedic note. The P. longus makes a chord for the 

 transverse arch of the foot, being the most important muscle to 

 preserve that arch from being flattened. 



