MUSCLES OF THE HAND. 



521 



3. Flexor brevis minimi digiti (unci-pfialan- 

 gien, Cruveilh.) This muscle is external to the 

 last; it arises from a small portion of the annu- 

 lar ligament and from the anterior part of the 

 unciform process ; it runs downwards and in- 

 wards to join the last described muscle, with 

 which it is inserted. 



Relations. At its origin it is separated from 

 the abductor by the ulnar vessels and nerve, 

 but it soon becomes confounded with it. 

 Chaussier described them both as one muscle. 

 It is often wanting. In concert with the last, 

 it abducts and slightly flexes the little finger. 



4. Adductor ossis metacarpi or opponens 

 minimi digiti ( unci-metacarpien, Cruveilh ) It 

 resembles in disposition and form the opponens 

 pollicis. Having the same origins with the 

 preceding muscle, its fibres proceed downwards 

 and inwards, the superior being nearly hori- 

 zontal ; they are inserted into all the internal 

 border of the fifth metacarpal bone. 



Relations. It is covered by the two last 

 muscles ; its posterior surface is applied to the 

 fifth metacarpal bone, the corresponding inter- 

 osseous, and the tendon of the flexor sublimis 

 going to the little finger. 



It carries the fifth metacarpal bone forwards 

 and outwards, thereby augmenting the cavity 

 of the hand, and in a measure opposing the 

 little finger to the thumb, but the articulation 

 of the metacarpal bone with the os unciforme 

 allows of so very little rotatory motion, that it 

 is rather a motion of adduction and tiexion 

 than of opposition. 



c. M uncles of the middle palmar region. 

 In the middle palmar region we have seven 

 muscles, four connected to the tendons of the 

 flexor profundus, the lumbricales, so called 

 from their resemblance to earth-worms; and 

 three deeper-seated muscles, the palmar inter- 

 ossei occupying a part of the second, third, and 

 fourth interosseous spaces between the meta- 

 carpal bones, the remaining part of those spaces 

 being filled up by muscles ; we shall presently 

 examine the dorsal interossei. 



1. Lumbricales (Jlectentes primum interno- 

 dium, Spig.) are four slender, elongated, fusi- 

 form, fleshy bundles, attached to the tendons of 

 the flexor profundus, just after it escapes from 

 under the annular ligament, distinguished into 

 first, second, &c. from without inwards. The 

 first arises from the fore and outer part of the 

 flexor profundus tendon belonging to the index 

 finger, sometimes also from the accompanying 

 tendon of the flexor sublimis ; the recoiid lum- 

 bricalis arises from the radial side of the tendon 

 of the same muscle destined to the middle 

 finger ; the third said fourth are double penni- 

 form arising from the opposed surfaces of the 

 three internal tendons of the same muscle; 

 from these attachments they proceed, the two 

 middle vertically downwards, the outer out- 

 wards, the inner inwards, towards the outer 

 side of the metacarpo-phalangeal articulations 

 of the fingers, where they end in flat broad 

 tendons, which are inserted into the outer 

 border of the common extensor tendon, in 

 common with the tendons of the correspond- 

 ing interossei with which they are confused ; 



they assist in completing the sheath which the 

 extensor tendons form for the back of the 

 fingers. 



Relations. Their anterior surface is covered 

 by the tendons of the flexor sublimis, by the 

 palmar aponeurosis, and collateral vessels and 

 nerves of the fingers. Their posterior surface 

 lies upon the interossei, the inferior transverse 

 metacarpal ligament, and the phalanges. 



Use. They assist in the flexion of the fingers 

 upon the metacarpus, at the same time drawing 

 them outwards, they steady the extensor ten- 

 dons, keeping them applied to the phalanges. 



The interossei, of which there are seven in all, 

 are small muscles situated between the meta- 

 carpal bones, to which they are attached supe- 

 riorly, their inferior attachment being to the 

 sides of the first phalanges and the extensor 

 communis tendons; there are three on the pal- 

 mar aspect, which are simple, and four on the 

 dorsal aspect of the hand, which are bifid mus- 

 cles ; there are two to each interosseous space, 

 excepting the first, which has only one : we 

 shall first examine the palmar interossei. 



2. Interossei interni digitorum manus, (meta- 

 carpo-p/ialangiens laterau.c palmaires, Chauss.) 

 Short, prismatic, and triangular; they arise, the 

 first, or posterior indicis, from the root and inner 

 side of the metacarpal bone of the fore-finger ; 

 the second, or prior annularis, from the root and 

 outer s.de of the metacarpal bone of the ring 

 finger ; the third, or interosseus auricularis, 

 from the root and outer side of the metacarpal 

 bone of the little finger. They extend along 

 the metacarpal bones, to which they are attach- 

 ed, and are inserted by short tendons; the 

 second and third in common w T ith those of the 

 lumbricales, into the outer and upper, and the 

 first into the inner and upper part of the corre- 

 sponding first phalanges and side of the exten- 

 sor tendons. 



Relations. Anteriorly they are covered by 

 the deep flexor tendons and palmar muscles ; 

 posteriorly they correspond to the dorsal inter- 

 ossei, which are also connected with them 

 along their unattached margin. 



Use. The simplest way of regarding their 

 action, which is rather complex, is to refer it 

 towards the axis of the hand or a central line 

 drawn through the third metacarpal bone and 

 the middle finger, in which case it is easily 

 perceived that the palmar interossei are adduc- 

 tors towards the axis of the hand. 



II. The only intrinsic muscles on the dorsal 

 aspect of the hand are the dorsal interossei, 

 interossei ejcterni digitorum manus. Their com- 

 mon points are, that they appear both on the 

 dorsal and palmar aspects of the hand ; they 

 are bicipital ; arising from the opposed surfaces 

 of two metacarpal bones, both heads termina- 

 ting in a common tendon, which is attached to 

 the sides of the first phalanges and extensor 

 tendons that are not supplied by the palmar in- 

 terossei. They are four in number; the first, 

 or adductor indicis, alone merits a particular 

 description. It is the largest ; arising from the 

 superior half of the external border of the first 

 metacarpal bone, and externally from all the 

 external surface of the second metacarpal bone; 



