184 



THE MUSCLES. 



Relations. Outer surface with the flexor profundus. Inner 

 surface with the radius, ulna, and interosseous membrane. 

 Action as indicated by the name. 



4. Muscles of the Hand. 



A. BETWEEN THE TENDONS. Mm. lumbricales (Fig. 

 88, f, f). Four small muscle in the palm of the hand. 



Origin by fleshy fibres from the outer (palmar) surface of 

 the tendon common to the ulnar four parts of the profundus (^'). 

 Insertion (f). The four slips are flat at their origin. 

 Each becomes cylindrical and curves 

 about the base of one of the four ulnar 

 digits and is inserted into the radial side of 

 the base of the first phalanx close to its 

 ventral border. 



Action. Bend the digits toward the 

 radial side. 



B. MUSCLES OF THE THUMB. M. 

 abductor brevis pollicis (Fig. 77, w) (in- 

 cludes also the opponens pollicis of man). 

 A very minute, probably rudimentary 

 muscle. 



Origin from the transverse ligament 



OF THE PALM OF THE (i) which connects the prominent fibrous, 

 hairless projection that lies over the pisi- 



a, M. flexor brevis polli- 

 cis; , M. adductor pollicis; form bone with the radial border of the 



C A- ^i te fl r sseU K f s T nd head of the radius. The muscle passes 



digit (M. flexor brevis dtgiti 



secundi); d, M. adductor radiodistad and ends in a very slender 



ST5V&/; tendon ' the insertion f which is int the 



M. interosseus of fourth base of the first phalanx of the thumb. 

 ^**lflERf M. flexor brevis pollicis (Fig. 89, ). 

 fifth digit (M. flexor brevis Origin by fleshy fibres from the ad- 



digiti quinti); t, M. ab- . ' 



ductor digiti quinti. 1-5, jacent borders of the os magnum and sca- 

 the digits in order. pholunar bones and from the fascia which 

 bridges the intervening groove for the flexor carpi radialis. 



Insertion by a short tendon into the base of the first 

 phalanx of the pollex. 



Action. Flexor of the thumb. 



FIG. 89. DEEP MUSCLES 



