I04 THE PRINCIPLES OF MYODYNAMICS. 



astragalus, at times, must be much greater than 

 45o pounds. This is especially the case when 

 external violence is added to muscular force. 



TOO. Let the foot-lever be extended as far as 

 possible ; from the origin of the contracting 

 muscles, taken collectively, let fall a perpendicu- 

 lar to the long axis of the foot prolonged 

 forward : The distance from the foot of this 

 perpendicular to the insertion of the contracting 

 muscles will show a large displacing component, 

 acting forward and upward. But it must be 

 kept in mind that the annular ligament, under 

 which the tendons of the muscles in question 

 run, modifies this theoretical conclusion. It will 

 appear that the myodynamic angle made by 

 any one of these muscles will always be acute. 

 And hence, the displacing coniponeid would act 

 backward and downward, and wozdd be repre- 

 sented by a line drawn fro7n the iiisertion of the 

 contracting muscles i7i the long axis of the foot 

 till it meets a perpendicular drawn fro7n the 

 annular ligament, where it passes over the teiidons, 



loi. (a.) Surgeons have found the foot dislo- 

 cated backward more frequently than forward. 



