THE PRINCIPLES OF MYODYNAMICS. IQ 



ents C R,or do and c d : The component d o presses 

 the movable bone against the fixed bone. The com- 

 ponent do is a MOVING or retentive component. 

 A7id the component c d is a displacing component 

 acting in the direction c d. But we have already 

 a displacing component i c acting in the opposite 

 direction, which will leave a displacijig component 

 equal i d. That is we micst dediut from the com- 

 ponent c i d the component i c which zuill leave the 

 component i d. That will be the displaciiig compon- 

 ent of the cont7^acti7ig muscle m. The lines o d and 

 i d represent the rectangular components of the 

 muscle. In a similar manner all rectangular 

 COMPONENTS may be found. 



id. The wheel and axle act on the principle 

 of the lever. 



Example : The rotation of the skull on the top 

 of the spinal column is an example of this prin- 

 ciple. 



1 1 . The agents which move the human body 

 are bones and muscles. The bones are passive 

 agents, and the muscles are active agents. 



12. Bones in regard to the action of muscles 

 may be divided into fixed and movable : — 



