QP MUSCULAR MOTION. 195 



not so much depend upon the strength of the contrac- 

 tion of the flexors, as upon the voluntary relaxation 

 of the extensors for our own relief. 



314. Every muscle has moreover a peculiar mecha- 

 nism,* adapted to the individual motions for which it 

 is intended. Besides the determinate figure of each, 

 many other kinds of assistance are afforded to their 

 peculiar motions. The bursa mucosa, chiefly found 

 among the muscles of the extremities ; the annular liga- 

 ments by which some are surrounded ; the fat in which" 

 most are imbedded; the lymphatic vapour around each ; 

 and, above all, the conformation of the sceleton, 

 chiefly in regard to apophyses, condyles, and articu- 

 lations; nay, even whole bones, v. c. the patella, the 

 pisiform of the carpus, and the sesamoid bones ;+ 

 are destined solely to facilitate the actions of certain 

 muscles. 



,315. In this mode is compensated; or at least dimi- 

 nished, that inevitable loss of power which necessarily 

 takes place from the conformation and stature of the 

 whole system, in which, from the acute angle at which 

 some muscles are inserted or the proximity of their 

 insertion to the centre of motion, much of that power 

 is lost which would have existed, if their insertion had 

 been more remote or at a more obtuse angle. % 



31G. The human body, possessing about 450 muscles, 



* P. J. Barthcz, Notivetle Mdchanique des Mouvcmens de VHomme et des 

 Animaux. Carcass. 1798. 4 to. 



•f- Mencc, of all animals which I have dissected, the mole is supplied with tlit> 

 most remarkable apparatus of sesamoid bones ; its anterior palmated feet, with 

 which it digs, have many of these bones, which greatly facilitate the action of 

 the brachial muscles. 



} Gilb. BJane, on Mmmlar Motion, p, 51. 



o 2 



