\ 



320 



Muscles of the Arm. 



lyigaiuentum carpi tiaiisversiiii 

 (cut through and turned back 



M. oppoiiens pollicis 



M. flexor pollicis brevis ._ 

 fsuporticial headi 



Groove for the m. flexor 

 pollicis longus 



M. flexor pollicis 

 brevis (deep head 



M. adductor ^ 



pollicis 



Tendon" of the 



ni. flexor pollicis 



longus 



(turned down) 



Os pisiforme 

 M. abductor 

 digiti V 



y' (cut off) 



Opening for a 

 branch of the 

 ' a. and n. ulnaris 



Ligamentum 

 - - carpi transversum 

 (cut through) 



M. opponens 

 digiti V 



Mm. 

 = . interossei 

 volares 



Mm. 

 -= interossei 

 ^. dorsales 



Ligamentum 



- capitulorum 



transversum 



Ligamentum 

 vaginale 



365. Deep muscles of the ball of the right thumb. 



(The 111111. iifxorcs digituriiiii , tlexur jioUicis long'us, ahiluctor ixjUicis Itrevis, abduetur digiti V 

 aud Hexor digiti V brevis have been removed ; the lig. carpi transversum has been cut through.) 



M. oppoiH'us pollicis (see also Fig. 364). Form: flat, oblong-quadrangular. Position : in 

 the ball of the thuiiil), almost completely covered by the m. abductor pollicis brevis. Origin: lig. 

 earpi transversum aud tuboreulum oss. multauguli majoiis. Insertion: corpus and capitulum oss. 

 nietacarpalis I. Action: it opposes the thumb to the other fingers. Innervation: n. medianus. 



M. flexor pollicis brevis (see also Figs. 363 and 364). Form: oblong-quadrangular. 

 I'usition: ulnar margin of the ball of the tbumb, in the depth, bounded radialward by the 

 ni. op]i< 'liens pollicis, ulnarward by the m. adductor pollicis. Origin: by two beads; superficial 

 head: lig. carjii transversum : deep head: ossa mullaugula, capitatum, metacarpale II. Insertion: 

 superficial head to the radial sesamoid bone, deep head by two divisions (one narrower, radial 

 and one thicker, ulnar) to the radial and ulnar sesamoid bones, both also to the base of the first 

 phalanx of the thumb and ])artly to tlie tendon of the m. extensor pollicis longus. Between 

 the two heads is a groove for the tendon of the m. flexor pollicis longus. Action: it flexes 

 the first and extends the second phalanx of the thumb. Innervation: superficial portions 

 by the n. medianus, dee]) by the ramus profundus of the ramus volaris manus n. ulnaris. 



M. adductor pollicis (see also Figs. 363 and 3()4). Form: fiat, triangular. Posi- 

 tion: in the depth of the 2)alm, immediately upon the bones and the mm. interossei; covered 

 by the tendons of the mm. fiexores digitorum , being bounded radialward by the preceding 

 muscle. Origin: os mi'tacarpale HI. Insertion: ulnar sesamoid bone, base of th(> first 

 pbalanx of the thumb and tendon of the m. extensor pollicis longus. Action: it adducts the 

 thumb and opposes it to the other fingers; it extends the second jihalanx of the thumb. 

 Innervation: ramus profundus of the ramus volaris manus n. tilnaris. 



M. oppoiieiis diu'iti quiiiti (0. T. o])ponens minimi digiti) (see also Figs. 363 and 364). Form : 

 tla , u'k,l..ng '(uadranguliir. Position; in the ball of the little finger, almost completely covered by 

 thv' Dam. aJxivvtor digiti V, aud flexor digiti V brevis. Origin: lig. earpi transversum and hamulus 

 oss. liamati. Insertion: corpus and e;i]iitiilum oss. metacarpalis V. Action: it draws the fifth 

 fi'iger toward tlil- thuii.'\ Innervation: ramus ])rofundus of the ramus volaris manus n. ulnaris. 



