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, /’).—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 (c’). 
Insertion (f').—TVhe 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. 
Ce re Origin from the transverse ligament 
OF THE PALM oF THE (1) which connects the prominent fibrous, 
HAND, __.. hairless projection that lies over the pisi- 
a, M. flexor brevis polli- ; : 
cis; 6, M. adductor pollicis; form bone with the radial border of the 
a AtAL. Hiexec brevis agi head of the radius. The muscle passes 
secundi); d, M. adductor radiodistad and ends in a very slender 
se letigee 3 eR aie tendon, the insertion of which is into the 
M. interosseus of fourth base of the first phalanx of the thumb. 
at receacator ML flexor brevis pollicis (Fig. 89, 2). 
fifth digit (M. flexor brevis Origin by fleshy fibres from the ad- 
dive ai peek ha 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. 
