168 MUSCULAR SYSTEM, 



rapaceous bird, the small thin cucullaris, (a, a,) Is seen ex- 

 tending outwards from the vertebral column, and above it 

 the two divisions of the latitsimus dorsi, (c, d,) which cover 

 also the infra spinatus, (b.} The short fleshy mass of the 

 deltoid muscle (/",) extends to the middle of the humerus, 

 and behind it is the long triceps extensor cubiti (g, h.) On 

 the fore-arm are seen the fleshy parts of the extensor carpi 

 radialis (i } ) with its long tendon passing over the end of the 

 radius, the supinator radii brevis (k,) the strong extensor digi- 

 torum communis (/,) and beneath this the extensor metacarpi 

 ulnaris (m, n,) which has its long tendon inserted into the 

 middle strong element of the single metacarpal bone in birds. 

 Beneath the thumb (<?,) is the very small flexor pollicis, and 

 on the ulnar side of the long middle finger (/*,) is the tendon 

 of the abductor indicis which passes down fleshy between the 

 long anchylosed metacarpal bone, and has its tendon inserted 

 into the base of the last phalanx. The flexor indicis has its 

 tendon inserted into the distal extremity of that phalanx (r.) 

 The flexor carpi ulnaris (p,) passes fleshy along the ulnar 

 side of the outer metacarpal bone, and the outer finger, con- 

 sisting of a single minute phalanx, has its own flexor digiti 

 minimi (s.) The muscles and articulations of the wing are 

 chiefly adapted for adduction and abduction, and they admit 

 of little flexion and extension, or promotion and supination, 

 excepting at the head of the humerus ; so that the whole 

 arm moves with greater solidity and effect as an organ of 

 flight, and is more easily folded along the side of the trunk 

 when in a state of repose. On the posterior extremities the 

 extensor muscles are more developed than the flexors from 



