152 HUMAN ANATOMY. 



humerus, between the upper part of the musculo-spiral groove 

 and the insertion of the teres minor, and from the external 

 internmscular septum; the internal head, from the posterior 

 aspect of the shaft of the humerus, below the insertion of the 

 teres major, and below the groove for the musculo-spiral nerve; 

 insertion, by a common head, into the posterior part of the under 

 surface of the olecranon process of the ulna ; action,, extends the 

 forearm; nerve, the musculo-spiral. 



SUBANCONEUS. Origin, from the posterior surface of the 

 humerus, above the olecranon fossa; insertion, into the posterior 

 ligament of the elbow-joint; action, draws up the posterior liga- 

 ment of the elbow-joint during extension of the forearm; nerve, 

 the musculo-spiral. 



MUSCLES OF THE FOREARM. 



Anterior Superficial Layer. 



PRONATOR RADII TERES. Origin, by two heads the smaller 

 from the coronoid process of the ulna, the larger from the 

 humerus, above the internal condyle, and from the common 

 tendon of this group of muscles, and intermuscular septum ; in- 

 sertion, into the outer aspect of the shaft of the radius; action, 

 pronates the hand; nerve, the median. 



FLEXOR CARPI RADIALIS. Origin, by the common ten- 

 don from the inner condyle, and from the intermuscular septum 

 between it and the pronator teres ; insertion, into the base of the 

 metacarpal bone of the index finger; action, flexes the wrist; 

 nerve, the median. 



PALMARIS LONGUS. Origin, from the inner condyle of the 

 humerus by the common tendon and the intermuscular septum 

 and the deep fascia ; insertion, into the annular ligament, spread- 

 ing out in the palmar fascia; action, renders tense the palmar 

 fascia; nerve, the median. 



FLEXOR CARPI ULNARIS. Origin, by two heads one by 

 the common tendon from the inner condyle of the humerus, 

 the other from the inner margin of the olecranon, the inter- 

 muscular septum, between the ulna and the flexor sublimis digi- 

 torum, and from the upper two-thirds of the posterior aspect 

 of the ulna; insertion, pisiform bone; action, flexes the wrist; 

 nerve, the ulnar. 



FLEXOR SUBLIMIS DIGITORUM (PERFORATUS). Origin, by 

 three heads one from the coronoid process of the ulna, above 

 the pronator radii teres, another from the common tendon from 

 the internal condyle of the humerus, and the third from the 



