THE MUSCLES. 165 



313. 14. Extensor digiti minimi proprius. 



Pos. : internal and close to the former, to the outer side of the 

 following muscle. Or.: united with the former muscle from 

 Condyl. extern. Ins. : united with the tendon of the M. extens. 

 commun. on the fifth finger. Use: assists in extending the fifth 

 finger. This muscle is often wanting. 



314. 15. Extensor carpi ulnaris (s. ulnaris externus). 



Pos. : on the ulnar border, covers the Ulna, M. supinat. brevis, 

 and the deep layer. Or. : Condylus externus humeri and the 

 Ulna (the central third of the posterior border). Ins. : Basis 

 oss. metacarpi V. Use : to extend the metacarpus and draw 

 (adduct) it rather inwards. 



0. Deep layer. 



315. 16. Abductor pollicis longus \_Extens.primiinternodii]. 

 Pos. : the most external, covered by extens. com., upon lig. 



inteross., Radius, the tendons of Mm. extens. radial, and the 

 outer side of the carpus. Or. : 1. Crista ulnx (below supinator 

 brevis) on the second fourth. 2. Lig. inteross. and Radius (pos- 

 terior surface). Ins. : Basis oss. metacarp. /., the free tendon in 

 a sheath. Use : to draw the thumb from the other fingers ; assists 

 in extending the hand and drawing it backwards. 



316. 17. Extensor pollicis brevis [Ext. secundi internodii]. 

 Pos. : internal, and ctose to the former muscle, only separated 



from it by a tendinous sheath. Or. : 1. Jlngulus extern. Ulnas. [?] 

 2. Lig. inteross. and Radius. Ins. : Basis Phalang. I. pol- 

 licis. Use : to extend the first phalanx, and then abduct the Os 

 metacarpi I. 



317. 18. Extensor pollicis longus [_Ext. tertii internodii^. 

 Pos. : between abduct, longus and extens. brevis pollic. Its 



tendon crosses over extens. radiall. (tendons), and is, on the car- 

 pus, separated from the tendon of abductor longus by a fossa. 

 Or. : Ulna (external surface, inferior half) and lig. inteross. Ins. : 

 Basis phalang. II. pollicis. Use : extends the ungual phalanx 

 of the thumb. 



318. 19. Extensor indicis proprius. 



Pos. : along the inner border of the former muscle, below it 

 and m. extens. carpi ulnar. and digit, commun. Or. : Ulna (ex- 

 ternal angle, middle) and lig. inteross. Ins. : the inner side of 

 the tendon of extens. comm. of second finger, on the second and 

 third phalanx. Use : to extend the index finger. 



Nerv. (fourteenth to nineteenth) interosseus externus. 



