158 MUSCLE TISSUE 



between which it is placed, most extensively from 

 that supporting the finger upon which it acts. The 

 tendon is inserted partly into the base of the first 

 phalanx and partly into the extensor tendon. 



The palmar inter ossei are three in number, are adduc- 

 tors, and each rises' from the lateral surface of the meta- 

 carpal of the finger on which it acts. They terminate 

 like the posterior tendons. The first belongs to the 

 ulnar side of the index, the second and third to the 

 radial sides of the ring and little fingers. 



The lumbricales are four small muscles, not always 

 well-defined. They arise from the tendons of the flexor 

 profundus digitorum. 



ACTIONS OF MUSCLES OF THE FOREARM AND HAND. 

 Pronation by the pronator teres and quadratus 

 and flexor carpi radialis slightly; pronator teres 

 flexes the forearm; can only pronate when the radius 

 is intact. 



Supination by the supinator brevis, biceps, and 

 supinator longus; the latter is a flexor of the elbow 

 and brings the forearm into midsupination. Radial 

 extensors of the wrist flex the elbow; others from the 

 external condyle extend. 



Flexion */ the wrist by the flexor carpi ulnaris and 

 radialis, by the flexors of the fingers and palmaris 

 longus. 



Extension of the wrist by the extensor carpi ulnaris, 

 the two radial extensors, and extensors of the fingers. 



Abduction of the wrist by the radial flexor and radial 

 extensors and extensors of the thumb. 



Adduction of the wrist by the flexor and extensor 

 carpi ulnares. The flexor carpi radialis and extensor 

 carpi ulnaris act on the radiocarpal joint; the flexor 

 carpi ulnaris and radial extensors on the midcarpal 

 joint. 



The extensors of the wrist are moderators of the 

 long flexors of the fingers; the flexors of the wrist 

 are moderators of the extensors of the fingers. 



