THE MUSCULAR SYSTEM 83 



tensor longus, hallucis, peroneus tertius, gastrocnemius, 

 plantaris, popliteus, flexor longus hallucis, flexor longus 

 digitorum, tibialis posticus, peroneus longus, peroneus 

 brevis. 



The deep fascia forms a complete investment of the 

 entire region of the leg, and is attached to the inner side 

 of the tibia. 



The tibialis anticus is a thick, fleshy muscle, situated on 

 the outer side of the tibia. It arises from the tuberosity 

 and shaft of the tibia, the fibers thereof terminating in a 

 tendon that passes under the annular ligament and is 

 inserted into the internal cuneiform bone and base of the 

 first metatarsal. Action, flexes the ankle-joint and raises 

 the inner border of the foot. Nerve, anterior tibial. 



The extensor longus hallucis is a thin, elongated, and 

 flattened muscle. It arises from the anterior surface of the 

 fibula and from the interosseous membrane ; the fibers pass 

 downward and terminate in a tendon that passes under the 

 annular ligament, and is inserted in the last phalanx of 

 the great toe. Action, same as the tibialis anticus. Nerve, 

 anterior tibial. 



The extensor longus digitorum is an elongated, flattened 

 muscle, situated most externally of all the muscles in front 

 of the leg. It arises from the tuberosity of the tibia 

 and shaft of the fibula, extends downward, and divides 

 into four tendons, which are inserted in second and third 

 phalanges of the four lesser toes. Action, extends the toes, 

 flexes the ankle, and everts the foot. Nerve, anterior 

 tibial. 



The gastrocnemius, the most important muscle of the X, 

 posterior part of the leg, is an elongated, flattened muscle. 

 It forms the calf proper. It arises from the condyles of 

 the femur by two heads. Insertion, with the tendons of 

 the soleus and plantaris to form the tendo Achillis, which 

 is finally inserted into the tuberosity of the os calcis. 



