THE MUSCLES OF THE LIMBS. 



51 



On the dorsal aspect : first, the peronceus tertlus for the 

 metatarsal bone ; secondly, one tendon from the extensor digi- 

 torum brevis, but this last is commonly absent in Man ; third- 

 ly, one tendon from the extensor digitorum longus. 



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Fig. 17. — Part of the middle digit of the maniis of an Orang with the flexors and extensors 

 of the phalanges : m<!/?., metacarpal bone ; Pli. 1, Pit. 2, Ph. 3, the three phalanges ; 

 -ffa-f. 1, the deep long extensor tendon from the extensor indicis ; Ed:t. 2, the supei-fi- 

 cial long extensor tendon from the ext&ntior commnnis ; I. fl., the interosseous short ex- 

 tensor ; /./., the interosseous short flexor ; F. pns.., the deep long flexor {perforaiis) ; F* 

 pis., the superficial long flexor (perforaius). 



On the ventral aspect : first, the jMronceus brevis, attached 

 to the base of the metatarsal ; secondly, two interossei ; 

 thirdly, a perforated flexor ; and fourthly, a perforating flexor, 

 like those of the manus. The divisions of the interossei, 

 wliich send tendons to the extensor sheath on the dorsum of 

 the digits of the foot in Man, are hardly distinct from the ven- 

 tral divisions of those muscles. 



In addition to the muscles vjrhich have been mentioned, the 

 fifth digit has an abductor and an adductor, which may be 

 rc^garded as subdivisions of the interossei, arising within the 

 manus or pes, and inserted into opposite sides of the proximal 

 phalanx ; and an opponens, a muscle attached to the ventral 

 face of the carpus or the tarsus, and inserted into the post- 

 axial edge of the shaft of the metacarpal or metatarsal. 



Finally, a lumbricalis muscle proceeds from the tendon of 

 the perforating flexor, on the pre-axial side of the digit, to 

 the extensor sheath. 



None of the other digits of the manus, or of the pes, has a 

 greater number of muscles than this ; in fact, all the others 

 have fewer muscles, some of those enumerated being sup- 



