THE CRURAL MUSCLES. 



657 



Outer tuberos j- 



ity of tibia ^. 



Head of fibula — *^ 



Calf muscles 



Peroneus 

 longus 



Intermuscular 

 septum 



Extensor longus 

 digitorum 



Extensor longus 

 hallucis 



Tubercle of tibia 



Calf muscles 



Tibialis anticus 



Its fibres are collected into a tendon which passes through the middle compartment 

 of the anterior annular ligament and is continued distally to the great toe. Over the 

 metatarso-phalangeal joint 



it spreads out into a mem- Fig. 624. 



branous expansion which 

 receives a tendon of the 

 extensor brevis digitorum 

 and is then continued dis- 

 tally to be inserted into the 

 first and second phalanges. 



Nerve-Supply. — By 

 the anterior tibial nerve from 

 the fourth and fifth lumbar 

 and first sacral nerves. 



Action. — To extend 

 the great toe and fiex the foot. 



Relations. — The ex- 

 tensor longus hallucis is cov- 

 ered in its upper part by 

 the tibialis anticus and the 

 extensor longus digitorum. 

 Near the ankle it crosses 

 obliquely over the anterior 

 tibial artery and passes upon 

 the foot between the ten- 

 dons of the extensor longus 

 digitorum and the tibialis 

 anticus, internal to the ar- 

 teria dorsalis pedis. 



Variations. — The muscle 

 is occasionally united at its 

 origin with the extensor longus 

 digitorum, and, in addition to 

 the connections which may ex- 

 ist between its tendon and that 

 of the long extensor, it may also 

 be connected with one of the 

 tendons of the extensor brevis 

 digitorum. 



A small muscle is some- 

 times to be found passing down- 

 ward alongside of the extensor 

 brevis hallucis to be inserted 

 into the base of the first meta- 

 tarsal. It may be termed the 

 abductor longus hallucis, and 

 takes its origin either from the 

 fibula close to the origin of 

 the extensor longus hallucis, or 

 from that muscle, or from the 

 extensor longus digitorum or 

 the tibialis anticus. 



What has been termed an 

 extensor brevis hallucis is fre- 

 quently represented by a slip 

 from the extensor longus hal- 

 lucis, the extensor longus digi- 

 torum, or even from the tibialis 



anticus inserting into the base of Muscles of anterior surface of right leg; extensor longus digitorum has 

 the first phalanx of the hallux. ^ been drawn aside to expose extensor longus hallucis. 



Peroneus brevis 



Peroneus tertius 



Anterior annular ligament 

 cut edge 



Outer malleolus 



Peroneus brevis tendon 

 Base of fifth metatarsus 



Abductor minimi digiti 



5. Peroneus Longus (Figs. 625, 629). 



Attachnnents. — The peroneus longus arises from the upper part of the lateral 

 surface of the fibula and from the intermuscular septa and crural fascia. Its fibres 



42 



