152 



COUES, 



Before noticing the individual muscles that act upon the wrist, we 

 should explain the necessity of changing the names of the so-called 

 flexors and extensors. The morphological position of the forearm is 

 with the bones uncrossed in strong supination. Then the palm looks 

 forward and downward, with the nails uppermost and pointing back- 

 ward; and in this position the hand is "symmetrical" with the foot, 

 the sole of which looks backward and downward, with the nails 

 pointing forward and upward. " Flexion " of a segment is its bend- 

 ing in the contrary direction to that of the segment above; as all 

 admit in the case of the foot, where " flexion" is decreasing the an- 

 gle formed between the front of the leg and the instep ; but the fact 

 has been strangely overlooked by most anatomists in the case of the 

 hand, where apparently its customary pronation has deceived them. 

 "Flexion" of the hand is the bending of that segment in the direc- 

 tion opposite to flexion of the forearm : that is, backward, remem- 

 bering the supine position of the member. The muscles that do this 

 lie upon the back of the forearm and hand, and correspond to those 

 upon the front of the leg and instep ; they are those called in anthro- 

 potomy the " extensors," but their function is flexion. We restore 

 their proper name, and similarly call the "flexors "of anthropoto- 

 mists, lying upon the front of the forearm, by their proper name of 

 extensors* There is to be no change in the digital flexors and ex- 

 tensors. 



The extensors (i.e., "flexors" of anthropotomy) of the wrist are 

 only two, ulnar and radial; both of large size. 



Extensor carpi radialis. — The first muscle on the ulnar side of the 

 pronator, interposed between this and the flexor digitorum com- 

 munis ; large, and of singularly flattened shape from side to side ; very 

 broad above, rather abruptly contracting to a very short and stout 

 tendon. It arises both fleshy and tendinous from the tip of the en- 

 tocondyle, and thence in a line across the bottom of the humerus in 

 front (dipping into the deep fossa there found) to the radial articula- 

 tion; and slightly from the head of the radius itself. The tendon, 

 barely one-third of an inch long, mounts a little way up the radial 

 border of the muscle : it is inserted by expanding upon and grasping, 

 as it were, the most prominent carpal bone upon the radial border of 

 the wrist. The usual action. 



* Consult further in this connection — 



Burt G. Wilder, On Morphology and Teleology, especially in the limbs of Mam- 

 malia. Mem. Bost. Soc. Nat. Hist., Vol. I. 1865. 



Jeffries Wyman, On Symmetry and Homology in Limbs. Proc. Bost. Soc. Nat. 

 Hist., p. 277. 1867. 



Elliott Coues, Antero-posterior Symmetry, with special reference to the Muscles 

 of the Limbs. New York Medical Record. July, 1870, et seqq. ; pp. 149-152, 193-195, 

 222-224, 272-274, 297-299, 370-372, 390-391, 438-440. 



