MUSCLES OF THE HAND. 213 



EXTENSOR Ossis METACARPI POLLICIS. 



Origin Posterior surface of shaft of ulna below the 



anconeus, from interosseous membrane, from middle 



third of shaft of radius. 

 Insertion Dorsal surface of base of metacarpal of 



thumb. 



Nerve Posterior interosseous. 

 EXTENSOR PRIMI INTERNODII POLLICIS. 



Origin Lies to the inner side of the metacarpal of 



the thumb, from lower third of shaft of radius and 



interosseous membrane. 

 Insertion Dorsal surface of base of first phalanx of 



thumb. 



Nerve Posterior interosseous. 

 EXTENSOR SECUNDI INTERNODII POLLICIS. 



Origin Posterior surface of shaft of ulna and inter- 

 osseous membrane. 



Insertion Base of last (or second) phalanx of thumb. 

 Nerve Posterior interosseous. 



MUSCLES OF THE HAND. 



Of the Thumb. 

 ABDUCTOR POLLICIS. 



Origin Ridge on trapezium and annular ligament. 

 Insertion Radial side of base of first phalanx. 

 Nerve Median. 

 OPPONENS POLLICIS. 



Origin From trapezium and annular ligament, ex- 

 ternal to abductor pollicis. 

 Insertion Radial side of metacarpal of thumb for 



entire length. 

 Nerve Median . 

 FLEXOR BREVIS POLLICIS. 



Origin Two heads, first, trapezium and annular 



