492 THE MUSCLES AND FASCIA 



the outer side of the tendon of the Flexor longus pollicis; and, becoming tendinous, 

 ha-s a sesamoid bone developed in its tendon, and is inserted into the outer side 

 of the base of the first phalanx of the thumb. The deeper portion of the muscle 

 is very small, and arises from the ulnar side of the first metacarpal bone beneath 

 the Adductor obliquus pollicis, and is inserted into the inner side of the base of 

 the first phalanx with this muscle. 



FIG. 369. Muscles of the left hand. Palmar surface. 



Relations. By its superficial surface, with the palmar fascia. Its deep surface is separated 

 from the Adductor obliquus pollicis by the tendon of the Flexor longus pollicis. By its external 

 (radial) surface, with the Opponens pollicis. 



