384 



THE MUSCULAE SYSTEM. 



"FLEXOR CARPI ULNARIS 



-FLEXOR DIGITORUM SUBLIMIS 

 FLEXOR CARPI RADIALIS 



;_PALMARIS LONGUS 



-Pisiform bone 



-ABDUCTOR POLLICIS LONGUS 



TRANSVERSE CARPAL 

 LIGAMENT 



ABDUCTOR DICUTI QUINTI 

 ABDUCTOR POLLICIS BREVIS 



FLEXOR DIGITI 

 "QUINTI BREVIS 

 ^FLEXOR POLLICIS 

 'BREVIS 



ADDUCTOR 

 POLLICIS 

 _ FLEXOR POLLICIS 



" LONGUS 



radiales, longus and brevis, (3) Extensor pollicis longus, (4) Extensor digitorum 

 communis and extensor indicis proprius, (5) Extensor digiti quinti proprius, 

 (6) Extensor carpi ulnaris. 



The thin deep fascia of the dorsum of the hand is lost over the expansions of 

 the extensor tendons on the fingers. Between the metacarpal bones a strong layer 

 of fascia covers and gives attachment to the interossei muscles. 



Aponeurosis Palmaris. The palmar aponeurosis is of considerable import- 

 ance. In the centre of the palm it forms a thick triangular membrane, the apex 



of which joins 

 the distal edge 

 of the trans- 

 verse carpal 

 ligament, and, 

 more superfici- 

 ally, receives the 

 insertion of the 

 tendon of the 

 palmaris longus 

 muscle. The 

 fascia separates 

 below into four 

 slips, one for 

 each finger. The 

 slips are con- 

 nected together 

 by transverse 

 fibres, which 

 form, beneath 

 the webs of the 

 fingers, the 

 superficial trans- 

 verse metacarpal 

 ligament (fasci- 

 culi transversi). 

 More distally 

 each slip separ- 

 ates into two 

 parts, to be con- 

 nected to the 

 sides of the 

 metacarpo- 

 phalangeal 

 joints and the 

 first phalanx of 

 the medial four 

 FIG. 343. SUPERFICIAL MUSCLES AND TENDONS IN THE PALM OF THE LEFT HAND, digits. In the 



cleft between 



the two halves of each slip the digital sheath is attached and extends distally on 

 to the finger. The lateral borders of this triangular central portion of the palmar 

 aponeurosis are continuous with thin layers of deep fascia, which cover and 

 envelop the muscles of the thenar and hypothenar eminences. The medial border 

 gives origin to the palmaris brevis muscle (p. 382). 



The digital sheaths (vaginae mucosae) are tubular envelopes extending along 

 the palmar aspect of the digits and enclosing the flexor tendons. Each consists of 

 a fibrous sheath attached to the lateral borders of the phalanges and inter-phalan- 

 geal joints, and continuous proximally with the palmar aponeurosis. Opposite each 

 inter- phalangeal articulation the digital sheath is loose and thin ; opposite the first 

 two phalanges (the first only in the case of the thumb) it becomes extremely thick, 

 and gives rise to the ligamenta vaginalia, which serve to keep the tendons closely 



LUMBRICAL MUSCLES 



x TENDONS OF FLEXOR DIGITORUM 



^SUBLIMIS 



FLEXOR DIGITORUM SUBLIMIS 

 FLEXOR DIGITORUM PROFUNDUS 



