76 



THE PRI^XIPLES OF MYODYXAMICS. 



(2.) In the same case, the distance of the 

 origin of the supinator longus from the head of 

 the radius was about four inches : Let the 

 dynamic triangle be right angled at the joint — ■ 

 the force of the sitpinator long its miLst be only 122 

 pounds to lift 50 pounds. Now, if we suppose 

 that, on the average, the supinator longus can 

 lift twice as much as the biceps brachii, then it 

 will follow that the supinator longus can lift as 

 much, on the average, as the biceps brachii and 

 the brachialis anticus. See Fig. 21. 



(3.) But, in a given case, according to the 

 above calculations, the supinator longus can lift 

 nearly three times as much as the biceps brachii. 

 The weight is lifted by means of the hand in 

 each instance. 



(4.) It must be remembered, however, that 

 the biceps brachii has a greater transverse sec- 

 tion than the supinator longus, and, -in this 

 respect, can exert more povv^er than the latter 

 muscle. The biceps brachii makes motion — the 

 supinator longus applies force. 



