216 MYOLOGY, OR ANATOMY OF MUSCULAR SYSTEM 



The Ulnar Region 



The following muscles constitute the hypothenar eminence-. 



1. M. abductor minimi digiti (abductor digiti quinti) rises 

 from the lower border and inner surface of the pisiform, almost 

 a continuation of the flexor carpi ulnaris; insertion, base of 

 the proximal phalanx of the little finger, ulnar side, and into 

 a sesamoid bone, sending a slip to the extensor tendon. 



2. M. flexor brevis minimi digiti is separated from the abductor 

 by deep branches of the ulnar nerve and artery, and rises 

 from the annular ligament and tip of the unciform process; 

 inserted into the base of the proximal phalanx by means of 

 a tendinous arch passing over the flexors, attached to the radial 

 and ulnar borders of the base. May be absent or fused with 

 abductor. 



3. M. opponens minimi digiti rises from the annular liga- 

 ment and unciform process to insert on the whole length of 

 the ulnar side of the fifth metacarpal and anterior surface of 

 its head. 



4. Palmaris brevis is a thin quadrilateral muscle placed 

 beneath the integument on the ulnar side of the hand. It 

 arises by tendinous fasciculi from the anterior annular liga- 

 ment and palmar fascia; passing inward it is inserted into the 

 skin on the inner border of the palm of the hand. 



The Middle Palmar Region 



The dorsal interossei are four in number, one for each space, 

 not rising above the level of the bones, and numbered from 

 without inward. Each rises from the two bones 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 proximal phalanx and partly into the extensor 

 tendon. Each abducts its finger from the middle line; two 

 are inserted into the middle finger, one on either side, one 

 into the radial side of the index, and one into the ulnar side 

 of the ring. The first dorsal interosseous is larger than the 

 others, called the abductor indicis; its outer head comes from 

 the proximal half of the ulnar border of the first metacarpal, 

 its inner from the whole length of the radial border of the 

 second metacarpal. 



