FLEXOR PROFUNDUS DIG I TO RUM 



319 



to the index finger, and part if not all of that l)elonging to the middle finger ui)on 

 the radial border of its anterior surface, about the middle of the forearm. (2) By 

 the ulnar nerve, which distriliutes l)ranches to the rest of the muscle near the inner 

 border of tlie sui)erficial aspect of the muscle in the ui)per part of the forearm. 

 Action. — It is a powerful fiexor of the third phalanges of the fingers. As with 



Fig. 275. — Front of the Fokkakm : Third Layer of Mu.scles. 



Biceps 



Muscles of the flrst and second 

 layers 



Flexor profundus digltorum 



Pronator quadratus 



Flexor carpi ulnaris 



Brachio-radialis 



Brachialis anticus 



Extensor carpi radialis lougior 

 Supinator brevis 



Flexor longus pollicis 



Brachio-radialis 



Extensor ossia metacarpi pollicis 



Estensor brevis pollicis 



the superficial fiexor, the extreme obliquity of the insertion of the tendons gives 

 great speed and range of movement, but "increases the mechanical disadvantage 

 with which this muscle (being a representative of the third order of lever) must 

 act. The slight elevation formed by the union of the two halves of each tendon of 

 the flexor sublimis upon the second phalanx diminishes to a small extent the 



