THE PRINCIPLES OE MYODYNAMICS. 



83 



point. And the muscles on the palmar aspect 

 of the upper limb are used more than the mus- 

 cles on the dorsal aspect of the upper limb, 

 because the former are habitually made to over- 

 come orreater resistintr forces than the latter. 



o o 



HcncL\ the flexors of the itpper limb are more 

 pozverfid tJuni the extensors. 



71. (a.) When the radius is completely ex- 

 tended the radio-humeral joint is conserved by : 



(i.) The retentive components of the supina- 

 tor longus and the biceps brachii. 



(2,) The retentive components of the pronator 

 radii teres and the supinator brevis. 



(b.) And the superior radio-ulnar joint is con- 

 served by the lateral retentive components of 

 the pronator radii teres and the supinator brevis. 



72. When the radius is semiflexed : 



(i.) The displacing component of the biceps 

 brachii will be large. 



(2.) The displacing component of the pronator 

 radii teres will be relatively small. 



(3.) The retentive component of the supinator 

 longus will be large, and its moving component 

 will not act as a displacing component. 



