26 THE PRINCIPLES OF MYODYNAMICS. 



bone, and may be called the displacing com- 

 ponent : — The conforination of the joint may be 

 such that the moving compone^it is a displacing 

 compo7tent : The moving component of the biceps 

 brachii is a displacing component. 



1 8. ^\\^ long axis of the contracting muscle, 

 the distance in the long axis of the movable bone 

 from the insertion of the contracting muscle to 

 the centre of the joint, and the distance in the 

 long axis of the fixed bone from the centre of 

 the joint to the origin of the contracting muscle 

 make the sides of a triangle, that may be called 

 the my 0 dynamic. triangle. — In Fig. 5, o i c is the 

 myodynamic triangle. 



19. That angle of the myodynamic triangle 

 included between the long axis of the contract- 

 ing muscle and the long axis of the movable 

 bone is important, and may be called the myo- 

 dynamic angle. In Fig. 5, o i c is the myody- 

 namic angle. 



(a) In the case of a bony lever of any order, the 

 myodynamic angle is the guide to the magnitu^des 

 of the recta7igidar compone7its of the contracting 

 muscle. 



