UPPER EXTREMITY AND THORAX, ANTERIOR. 309 



Nerve Supply. The ulnar, through the deep branch ; the 

 filaments coming from the eighth cervical nerve. 



Action. To adduct and flex the carpometacarpal joint, 

 to flex this and the metacarpophalangeal joints. By its 

 attachment to the extensor aponeurosis it will extend the 

 last phalanx of the thumb. 



Opponens Pollicis. Fig. 67. 



Origin. From the annular ligament and the ridge of the 

 trapezium. 



Insertion. Into the front of the metacarpal bone of the 

 thumb. 



Nerve Supply. The median from the sixth cervical nerve. 



Action. To flex and adduct the metacarpal bone of the 

 thumb. 



Opponens Minimi Dig-iti. Fig. 67. 



Origin. From the annular ligament and the hook of the 

 unciform bone. 



Insertion. Into the entire length of the inner border of 

 the fifth metacarpal bone. 



Nerve Supply. The ulnar nerve from the eighth cervical. 



Action. Flexion and adduction (slight) of the fifth meta- 

 carpal bone. 



Palmar Interossei. (Three.) 



Origin. From the side of the metacarpal bones of the 

 index, ring, and little fingers. The first arises from the 

 inner, the second and third from the outer side of the re- 

 spective metacarpal bones. 



Insertion. Into the base of the first phalanges of the 

 corresponding fingers, and by an extension into the apon- 

 eurosis of the extensor tendons. The first being inserted 

 on the inner, the second and third into the outer sides of 

 their respective fingers. 



