WILDER ON MORPHOLOGY AND TELEOLOGY 



general plan of the muscles any more than if the fore-arm were, in some one species, 

 broken, and thus movable at the middle of its length, some of the muscles being inserted 

 upon the proximal, and others upon the distal moiety. Moreover, the muscles specially 

 connected with this joint, lie all upon the same side of the limb ; namely, with the flexors 

 of the fore-arm and the extensors of the hand, while, if it were a real joint, we should 

 expect to find the supinators or extensors on the same side as the flexors of the fore-arm, 

 and the pronators or flexors on the same side with the extensors of the hand ; but in fact, 

 as before stated, they all lie upon the same side ; whereby the long supinator and pronator 

 are both made to assist the flexion of the fore-arm, which is evidently of more importance 

 than its extension. The radio-ulnar articulation is therefore a teleological interpolation, 

 presenting none of the characters of a true joint between the real segments of a limb. 



The two opposite movements of pronation and supination are performed by two sets of 

 muscles ; those of one set are short, the pronator quadratus and supinator brevis, arising from 

 the ulna, the first segment above their insertion ; those of the other set are long, the pro- 

 nator teres and supinator longus, arising from the humerus or second segment above their 

 insertion ; and here, as with the muscles of the true joints, the short muscles have but one 

 action, to move the radius or counteract each other ; while the long ones either act directly 

 in a similar manner or indirectly flex the fore-arm, the segment which, as to its fixed bone, 

 the ulna, intervenes between their origins on the humerus and their insertions on the 

 radius. The biceps is really the most powerful supinator of the radius, and can turn the 

 palm of the hand completely upward; while the two supinatores can only bring the 

 thumb or radial border of the hand uppermost. There are four muscles acting directly 

 upon the hand, (carpus and metacarpus ;) two flexors, radial and ulnar, and two exten- 

 sors, radial and ulnar ; the ulnar flexor and extensor arise chiefly from the bones of the fore- 

 arm, and are the short muscles, since they come from the first segment above that to be 

 moved, and the two radial are the long muscles arising from the humerus, the second 

 segment above. The long, or radial extensor, is also the indirect flexor of the fore-arm, 

 and perhaps, morphologically, the radial flexor is the indirect extensor of the same inter- 

 mediate segment, though I am not aware that it ever is so actually ; and on the contrary, 

 when, as in the horse, the humeral condyles are wanting, the extensor arises on the 



inner 



side, below the centre of motion, and would thus act as an extensor of the fore-arm, while the 

 flexor arises from the outer side above the centre of motion, and is therefore physiologically 

 a flexor of the same segment. 



If we regard the fingers as a single segment, then there is a short and a long flexor, 

 flexor communis sublimis and flexor communis profimdus ; but these would then seem to arise 

 each from one segment above what would be expected ; the former from the humerus, 

 and the latter from the fore-arm ; but the insertion of a muscle is of more importance mor- 

 phologically than its origin, which latter is in relation to the required length of the muscle 

 and the proportion of parts, and therefore more liable to vary ; so, taking the less modified 

 foot for comparison, it seems more natural to suppose that the flexor profundus is, morpho- 

 logically, the long flexor, and the flexor sublimis the short ; its origin having been moved 

 upward two segments on account of the very extensive movements required of the fingers, 

 more extensive in proportion to their size than those of any other part of the body. 



With this view, the short flexor of the fingers, like the short flexor and extensor of the 

 toes, is inserted into the second phalanges. That the proper short palmar muscles of the 

 thumb and little finger are not the true representatives of the short flexor is shown by 

 their co-existence in the foot with an unmistakable short flexor. There is no long extensor 



