74 THE PRI^XIPLES OF MYODYXAMICS. 



(3.) The lateral components will be resolved 

 into rotatiiig and retciitive components : — (a) 

 The retentive components will hold the radius 

 against the ulna: — (b.) The rotating components 

 will rotate the radius. 



(4.) The lateral retentive components of the 

 special supinators are greater than the rotating 

 components of these muscles. 



(5) Hence, the forces of the special outro- 

 tators of the fore-arm act in a conservative 

 manner in so far as the radio-ulnar joint is con- 

 cerned. 



62. The function of the supinator longns de- 

 serves special attention. 



(i.) In the first place, when the fore-arm is 

 completely extended, the origin of the supina- 

 tor lonorus will be nearlv in a line with the axis 

 of the radial cone, and as the radius rotates in- 

 and-out. the long axis of the supinator longus 

 will coincide nearly with the slant-height of the 

 radial cone : — So that, under the circnnistances, 

 the supinator longus will not be a strong rotator. 



(2.) In the second place, flex the fore-arm 

 until it makes a rieht anele with the arm. and 



