EXTEXSOE PEOPEIUS POLLICIS MUSCLE. 245 



outer malleolus to the outer surface of the ealcaneum, and keeps in 

 place the tendons of the long and short perouei muscles. The tendons 

 are close together, and are surrounded by one sj-novial sac. 



The dorsal fascia of the foot is reduced to a thin membrane pro- 

 longed fi'om the anterior annular ligament over the extensor tendons. 

 Beneath it, deeper layers of fascite are placed over the short extensor of 

 the toes and the interossei muscles. 



Muscles. — Betvreen the tibia and fibula, and on the front of the leg, 

 are placed four muscles — the tibialis anticus, extensor proprius pollicis, 

 extensor longus digitorum, and peroneus tertius ; and on the dorsum 

 of the foot one muscle only arises, — the extensor brevis digitorum. 



The tibialis anticus arises from the external tuberosity of the tibia, 

 and about two-thirds of the outer surface of that bone ; from a small 

 portion of the adjoining interosseous ligament ; from the strong fascia of 

 the leg ; and fi'om an aponeurotic septum placed between it and the 

 extensor longus digitorum. The tendon glides in a synovial sheath 

 beneath the anterior annular ligament, and is inserted into the inner 

 and lower part of the internal cuneiform and the contiguous extremity 

 of the first metatarsal bone, dividing slightly into two slips as it 

 descends. 



Bchifions. — This muscle is entii'ely covered by the aponeurosis of the leg. It 

 rests upon the outer sui-face of the tibia, and the interosseous ligament. Its 

 outer surface is in contact above with the extensor longus digitoinim. and lower 

 down with the extensor proprius pollicis ; it also conceals the anterior tibial 

 vessels and nerve. Its tendon passes over the lower end of the tibia, the ankle- 

 jomt, and the inner surface of the tarsus. 



VarietU-K. — In cases of talipes the tendon of this muscle has been found split 

 into two, one half going to the usual place of insertion, the other to the astra- 

 galus or first metatarsal ; the whole tendon has also been seen inserted into the 

 plantar fascia. The fihio-fa.scuili.t <inticus is a small muscle described by "Wood, 

 arising from the lower third of the anterior edge of the tibia over the tibialis 

 anticus and inserted into the annular ligament and deep tibial fascia. It may 

 also exist as a tendinous slip from the tibialis anticus. 



The extensor proprius pollicis pedis muscle, or extensor hal- 

 lucis, placed between the tibialis anticus and the extensor longus 

 digitorum, arises from the middle three-fifths of the anterior narrow 

 part of the inner surface of the fibula, and from the contiguous portion 

 of the interosseous ligament. Its tendon passes through a distinct 

 compartment in the lower portion of the annular ligament in and 

 along the dorsum of the foot, to be inserted into the base of the ter- 

 minal phalanx of the great toe. A delicate expansion given off from 

 the tendon on each side spreads over the joint between the metatarsal 

 bone and the first phalanx. 



lidfifwn-i. — This muscle is partly concealed by those between which it is placed. 

 It lies external to the anterior tibial artery in the leg, but crosses in front of 

 that vessel at the bend of the ankle, and is internal to it on the foot. 



Vtn-U'fics: — The cvtcnwr ossifs mctafaviii jwlliri.s is a small muscle, sometimes 

 found as a slip from the extensor proprius, or from the tibialis anticus. or from 

 the extensor communis digitorum ; or it may be a distmct muscle arising close 

 to the extensor projirius, and traversing the same compartment of the annular 

 ligament with that muscle. 



The ci'ten-sor jn-ii/ii intenwdil j^oUicU, another occasional muscle is nearly 

 always an offshoot from the extensor jiroprius. though it has been found 

 separate. It was seen by Wood in one half of the subjects extvmined by him. 



