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U.S. NATIONAL MUSEUM BULLETIN 2 73 



pollicis tendon, but only on the first phalanx (see Napier, 1952; 

 and Wood Jones, 1949). 



Nerve supply: A branch is given off for both the abductor pol- 

 licis brevis and the short flexor by the median nerve just before 

 it divides into its sensory branches to the poUex, index, and half 

 of the middle finger. 



Function: It appears to be more of a flexor than an abductor 

 of the thumb. 



Figure 34. — Muscles of the hand (1, m. abductor pollicis brevis; 2, m. flexor pollicis brevis, 

 caput radiale; 3, m. flexor pollicis brevis, caput ulnare; 4, m. flexor pollicis brevis, caput 

 profundum; 5, m. opponens pollicis; 6, m. contrahens II; 7, m. adductor pollicis; 8, m. 

 contrahens V; 9, m. flexor digiti quinti (= flexor digiti minimi of N.A.); 10, m. opponens 

 digiti quinti (=opponens digiti minimi of N.A.); 11, m. abductor digiti quinti (=abductor 

 digiti minimi of N.A.). 



M. flexor pollicis brevis: This two-headed muscle is partially cov- 

 ered by the preceding and therefore occupies an intermediate position 

 in depth within the thenar compartment (figs. 32, 33, 34). A caput 

 radiale arises by strong fleshy fibers from the scaphoid and radial 

 carpal sesamoid. The strong belly runs under that of the short ab- 



