30 THE PRINCIPLES OF MYODYNAMICS. 



long axis of the fixed bone from the origin of 

 the contracting muscle to the joint. 



(c) When the myodynamic angle is right, the 

 long axis of the contracting muscle will be the 

 perpendicular drawn from the origin of the mus- 

 cle to the movable bone : The component o d 

 will coincide with the long axis of the muscle ; 

 and there will be one rectangular component. 

 See Fig. 6. The component d c which is sup- 

 posed to make part of the resultant m is exactly 

 equal the component c d, which makes part of 

 the resultant s i, or o c : and these components 

 neutralize each other. 



(d) When the myodynamic angle is acutey or 

 obtuse, the perpendicular drawn from the origin 

 of the contracting muscle to the movable bone 

 will fall outside the long axis of the muscle, and 

 there will be two rectangular components. See 

 Figs. 5 and 7. The displacing component will 

 be represented by the line i d. 



22. A. When the myodynamic angle varies, 

 the magnitudes of the rectangular components 

 will vary. The following laws of variation in 



