FOREARM AND HAND 141 



the medial epicondyle of the humerus and the olecranon, and 

 between them the ulnar nerve is prolonged distally into the 

 forearm. The tendon appears upon the volar border of the 

 muscle, and is inserted into the pisiform bone. The flexor 

 carpi ulnaris is supplied by the ulnar nerve. It is a flexor 

 and adductor of the hand and a flexor of the elbow. 



M. Flexor Digitonun Sublimis. The flexor sublimis re- 

 ceives this name because it is placed upon the superficial 

 aspect of the flexor profundus. For the most part it lies 

 deeper than the other superficial muscles (Fig. 61). It is a 

 powerful muscle which arises from the medial epicondyle of 

 the humerus by the common tendon it takes origin also 

 from the ulnar collateral ligament of the elbow- joint, from 

 the medial margin of the coronoid process of the ulna, the 

 volar surface of the radius (Figs. 45, 64), and the fascial 

 intermuscular septa in relation to it. The radial head of 

 origin is a thin fleshy stratum which is attached to the 

 volar border of the radius, from its proximal end to a 

 variable distance beyond the insertion of the pronator teres 

 muscle. Four tendons issue from the fleshy mass ; they 

 enter the palm by passing under cover of the transverse carpal 

 ligament, and go to the medial four digits. Their insertions 

 will be seen later, but, in the meantime, note that at the wrist, 

 and for a short distance proximal to it, they are enveloped 

 by the mucous sheath previously mentioned, and also that, as 

 they pass behind the transverse carpal ligament, they lie in 

 pairs the tendons to the ring and middle fingers being placed 

 on the volar aspect of those for the index and little fingers. 

 The flexor digitorum sublimis is supplied by the median 

 nerve. It is a flexor of the first interphalangeal joints of 

 the fingers, the metacarpo-phalangeal joints, the wrist joint, 

 and the elbow joint. 



The dissector who examines the flexor digitorum sublimis in detail 

 will find that the part which arises from the humerus divides into 

 a superficial and a deep portion, and that each portion subdivides 

 in two parts, a lateral and a medial. The lateral part of the superficial 

 portion unites with fibres which spring from the radius ; then the combined 

 fibres pass to the tendon for the middle finger. The medial part of 

 the superficial portion receives additional fibres from the deeper portion, 

 and ends in the tendon for the ring finger. The lateral part of the 

 deeper portion is a digastric muscle ; it ends in the tendon for the 

 index finger. The medial part of the deeper portion ends in the tendon 

 for the little finger ; it is a small muscular belly which frequently 

 receives fibres from the intermediate tendon of the lateral part of the 

 deeper portion of the muscle. 



