612 



TEXTBOOK OF ZOOLOGY 



femur is the bone of the thigh which fits close to the body and is 

 covered by the feathers. The section below the knee (shank) is com- 

 posed of the long, larger tibiotarsus and the slender fibula which is 

 more or less free at the proximal end but is bound to the tibiotarsus 

 along its side. The next portion is a single bone, the tarsometatarsus, 

 which has resulted from a fusion of several. Distal to it are attached 

 the four digits, each composed of phalanges. The first toe is directed 

 backward and the other three forward, as an adaptation for perching. 

 In the male chicken there is a horny spur projecting backward from 

 the tarsometatarsus. 



BICEPS 

 DELTOID 



EXTENSOR METACARPI 

 RADIALIS LONGUS 

 PRONATOR BREVIS 

 EXTENSOR INDICIS LONGUS 

 EXTENSOR OSSIS 

 METACARPI POLLICIS 

 FLEXOR DIGITORUM 



FLEXOR CARPI ULNARIS 



EXTENSOR PROPRIUS POLLICIS 

 FLEXOR BREVIS POLLICIS 

 INTEROSSEOUS PALMARIS 



Fig. 327. — Ventral view of the muscles of the wing of a chicken. (Drawn by 



Titus Evans.) 



Muscular System 



In the chicken there are 162 voluntary, striated muscles, single 

 or in pairs. These muscles are named in some cases from their loca- 

 tion, others from their attachments, some for their shape and form, 

 others from their use or function, and still others from their direc- 

 tion in the body. They are covered and bound together by the white 

 fibrous connective tissue sheath, called fascia. 



The muscles of the chest and forelimb are quite well developed 

 as an adaptation to flight. The muscles of the thigh and shank are 



