108 ANATOMY OF VERTEBRATES. 



malleolus, and is finally inserted or continued into the perforated 

 tendon of the middle toe. 



The tibialis anticus, ' fig. 35, 48, is overlapped and concealed 

 by the peroneus ; it arises partly in common with that muscle, 

 and partly by separate short tendinous threads from the outer 

 part of the head of the tibia ; it gradually becomes narrower, and 

 finally tendinous two-tlnrds of the Avay down the leg ; its strong 

 tendon glides through the oblique pulley^ in front of the distal 

 end of the tibia, expands as it passes over the ankle-joint, and is 

 inserted into the anterior part of the proximal end of the tarso- 

 metatarsal bone, sending off a small tendinous slip to the aponeu- 

 rosis covering the extensor tendons of the toes, and a strong 

 tendon which joins the fibular side of the tendon of the following 

 muscle. 



Extensor longus digitorum.^ This lies between the tibialis 

 anticus and the front and outer facet of the tibia, from which it 

 derives an extensive origin ; its tendon commences half-way down 

 the leg, runs along the anterior part of the bone, first under the 

 broad ligamentous band representing the anterior })art of the 

 annular ligament, then through a ligamentous pulley, and inclines 

 to the inner or tibial side of the anterior surface of the metatarsal 

 bone, where it expands and divides into three tendons. Of these 

 the innermost is given off first, and subdivides into two tendons, 

 one of which goes to be inserted into the base of the last phalanx 

 of the second toe; the other portion is principally inserted into 

 the middle toe, but also sends off a small tendon to the inner side 

 of the proximal phalanx of the second toe. The second tendon 

 is inserted by distinct portions into the second, third, and last 

 phalanges of the middle toe. The third tendon supplies the outer toe. 



The extensor brevis digitorum "^ is a small extensor muscle which 

 arises from the insertion of the tibialis anticus and sends its tendon 

 to the outer side of that of the great extensor digitorum. 



Extensor pollicis brevis.^ This extensor of the small innermost 

 toe arises from the upper and inner side of the tarso-metatarsal 

 bone. 



Peroneus medius, Cuv., Accessorius flexor is digitorum, Yicq. 

 d'Azyr.^ This strong 2:)enniform muscle arises fleshy from nearly 

 the Vvdiole of the outer surface of the fibula, also from the posterior 

 part of the tibia and the interosseous space ; the tendon of the 

 biceps perforates its upper part in passing to its insertion. It 



' xr. vol. iii. pis. 32, 3.5, 8. '^ This is ossified in most Birds. ^ lb. pi, 35, 9. 



* lb. pi. 35, 10. ^ lb. pi. 35, 1 J. ^ lb. pis. 32, 35, 12. 



