ACTIONS OF VOLUNTAEY MUSCLES. 467 



It is still better shown in the arteries, of which all that have 

 muscular coats contract after death, and thus present the 

 roundness and cord-like feel of the arteries of a limb lately re- 

 moved, or those of a body recently dead. Subsequently they 

 relax, as do all the other muscles, and feel lax and flabby, and 

 lie as if flattened, and with their walls nearly in contact. 1 



Actions of the Voluntary Muscles. 



The greater part of the voluntary muscles of the body act 

 as sources of power for moving levers, the latter consisting 

 of the various bones to which the muscles are attached. 



All levers have been divided into three kinds, according to 

 the relative position of the power, the weight to be moved, and 

 the axis of motion or fulcrum. In a lever of the first kind the 

 power is at one extremity of the lever, the weight at the other, 

 and the fulcrum between the two. If the initial letters only 

 of the power, weight, and fulcrum be used, the arrangement 

 will stand thus: P.F.W. A poker, as ordinarily used, or 

 the bar in Fig. 164, may be cited as an example of this variety 

 of lever ; while as an instance in which the bones of the human 

 skeleton are used as a lever of the same kind, may be men- 

 tioned the act of raising the body from the stooping posture 

 by means of the hamstring muscles attached to the tuberosity 

 of the ischium (Fig. 163). 



In a lever of the second kind, the arrangement is thus : 

 P.W.F. ; and this leverage is employed in the act of raising 

 the handles of a wheelbarrow, or in stretching an elastic band, 

 as in Fig. 164. In the human body the act of opening the 



1 Although the preceding remarks represent the views generally 

 entertained in regard to muscular action, yet it must be observed 

 that a new and very different theory on the subject has been lately 

 advanced by several writers, and especially developed by Dr. Rad- 

 cliffe, who has also made it the basis of new views on the pathology of 

 various convulsive affections. According to this doctrine, the ordi- 

 nary relaxed or elongated state of a muscle is due to a certain " state 

 of polarity" in which the muscle is maintained, and contraction is 

 brought about by anything (such as an effort of the will) which lib- 

 erates the muscle from this influence, and thus leaves it to the opera- 

 tion of the attractive force inherent in the muscular molecules. Ac- 

 cording to this doctrine, also, the stage of rigor mortis is readily 

 explicable : death depriving the muscles of the " state of polarity'" 

 whereby they had hitherto been kept relaxed, and thus allowing the 

 attractive force of the muscular particles to come into play. For 

 facts and arguments in support of this view, and for references and 

 confirmatory opinions, Dr. Radcliffe's work on epileptic and other 

 convulsive affections may be consulted. 



