MUSCULAR MOTION. 359 



never cease their actions for any long interval. It is worthy of 

 remark, that apoplexy and other cerebral affections, paralyze, 

 most commonly, the voluntary muscles alone, while the others 

 retain their usual state and sensibilities. 



When irritability is entirely gone from a muscle, and it is 

 actually dead, the whole muscular system becomes stiff, begin- 

 ning with the trunk, then the inferior, and, lastly, the superior 

 extremities. This stiffness seems to be independent of the ner- 

 vous system, as the destruction of the spinal marrow, the cut- 

 ting of nerves, and hemiplegia do not arrest it. It is thought, 

 by M. Beclard, to be analogous to the contraction of the fibrine 

 of the blood; and, like the latter, does not cease till putrefac- 

 tion begins. The degree, as well as the time, of its access is 

 variable under different circumstances. In very aged persons; 

 in such as have died from protracted disease attended with 

 great emaciation ; in scorbutic and gangrenous diseases, the 

 stiffness comes on quickly, is very slight, and disappears in a 

 couple of hours. But in muscular subjects who have died from 

 sudden violence or from acute diseases, the stiffness is some- 

 times postponed for twelve hours or more, and may continue, 

 in the winter, from three or four days to a week, or even 

 longer, depending upon the access of putrefaction. 



The sensibility of the muscles is moderate. When they have 

 been much exercised, they only give out the sensation of fa- 

 tigue. In amputations, the pain of cutting through them is not 

 equal to that of the skin. In inflammations they, as most other 

 parts, have their sensibility exalted to an exquisite degree. 



CHAPTER III. 



OF THE MECHANICAL SHAPE AND ARRANGEMENT OF THE 

 VOLUNTARY MUSCLES. 



EVERY muscle consists in a belly and in two extremities, of 

 which the one that is the fixed point is the head or origin, and 

 the other is the tail or insertion. The belly or body is the 

 fleshy part, the extremities are generally tendinous, either com- 

 pletely or partially. 



