MUSCLES OF THE HAND. 



519 



of them, whether voluntary or communicated 

 to them, are painful ; and in either case com- 

 monly a crepitus, produced by the contact of 

 rough surfaces, is perceived both by patient 

 and physician when making the examination. 



When this disease exists in the hand to this 

 amount, it will almost invariably be found that 

 the distressing complaint has also extensively 

 engaged most of the other articulations. 



When we make an anatomical examination 

 of the hand of those who have died with the 

 condition of the joints of the fingers above 

 described, we find that the synovial fluid is 

 somewhat thicker than usual, and deficient in 

 quantity. In some of the anchylosed joints we 

 observe a species of fibro-cellular or ligamentous 

 union of the bones; almost all the joints are de- 

 prived of their cartilaginous incrustation, which 

 seems as it were to have been worn away by 

 friction ; the porous structure of the root of the 

 phalanges is often exposed, and in some cases 

 hollowed out, to accommodate the enlarged 

 head of the metacarpal bone ; a cup is formed in 

 the base of the phalanx which is lined with a 

 porcelainous deposit, while around this little 

 cup an exuberant growth of new bone of a 

 looser texture is thrown out. In the removal 

 of the cartilage without suppuration in the 

 substitution for it of a porcelain-like deposit, 

 and in the surrounding exuberance of new 

 bone, we find this disease of nodosity of the 

 joints of the fingers resembling accurately the 

 analogous affection of the other joints, which 

 has been supposed to be the slow effects of 

 chronic rheumatism. See ELBOW, KNEE, HIP, 

 ABNORMAL ANATOMY OF. 



III. CONGENITAL MALFORMATIONS OF THE 

 HAND. 



Children are occasionally born with one or 

 two fingers more than the natural number. The 

 supernumerary finger almost invariably is found 

 to be an imperfect vegetation, growing from the 

 ulnar side of the hand, and in general the 

 deformity is found to exist on both hands. 

 Examples, however, have been, though rarely, 

 seen of a sixth finger parallel to the other fin- 

 gers, and properly supported by a sixth meta- 

 carpal bone. 



It frequently happens that children are 

 brought into the world with their fingers united 

 together. This union may be complete, or the 

 connexion may be loose by means of the skin. 

 It is known that up to the second or third month 

 of intra-uterine life an interdigital membrane 

 exists, and the abnormal condition of the fin- 

 gers we are now considering is nothing 

 but a persistence of the early condition 

 of the fingers in the foetal state. It seems 

 pretty well proved that these congenital defects 

 are very frequently hereditary, and that when- 

 ever the fingers are the seat of them, the toes 

 are similarly affected. 



The whole hand, or one or more of the fin- 

 gers may suffer in utero what has been denomi- 

 nated spontaneous amputation, and the stump 

 will present peculiarities already noticed. See 

 Fai LS, jig. 155, 159. 



(R.Adams.) 



HAND, MUSCLES OF THE. (Human 

 Anatomy.) The varied and beautiful move- 

 ments of which the hand is capable are effected 

 by muscles belonging to separate and distinct 

 regions, namely, one set of muscles which are 

 the proper and intrinsic muscles of the hand 

 itself, and a second set, which are continued into 

 the dorsal or palmar region of the hand from 

 the posterior or anterior surface of the fore-arm. 

 In the present article it is proposed to describe 

 the intrinsic muscles of the hand ; but in con- 

 sidering the actions of that member or of any 

 of its segments, it will be necessary to notice 

 how far the second set of muscles contribute to 

 or aid in their production. 



The proper or intrinsic muscles of the hand 

 may be divided into 1, those on the palmar; 

 2, those on the dorsal surface. 



I. The muscles of the palm are fifteen in 

 all. For convenience of description they may 

 be classified into, a, those of the thumb, or 

 external palmar region, constituting the thenar 

 eminence ; b, those of the little finger, or in- 

 ternal palmar region, forming the hypothenar 

 eminence ; c, those that occupy the hollow of 

 the hand, or the middle palmar region. 



a. Muscles of the external palmar region. 

 The muscles of this region, all of which belong 

 to the thumb, are four. 



1. Abductor pollicis manus* (scaphoido- 

 phalangien, Cruveilh.) short, flat, broader above 

 than below ; it arises from the anterior surface 

 of the scaphoid and trapezium, the superior, 

 anterior, and external part of the anterior annu- 

 lar ligament, and generally from a prolongation 

 of the tendon of the extensor ossis metacarpi, 

 by aponeurotic and fleshy fibres. It proceeds 

 outwards and downwards to be inserted into 

 the outer edge of the upper extremity of the 

 first phalanx of the thumb. Sometimes the 

 two origins of this muscle are not incorporated 

 for some distance, giving the appearance of 

 two muscles. 



Relations. It is covered by the skin and 

 external palmar aponeurosis. It covers the 

 opponens, a few fibres of which appear to its 

 radial side, running in a transverse direction. 

 It is separated by a thin cellular line from the 

 short flexor, which is on the same plane. 



The obvious action of this muscle is to draw 

 the thumb forwards and inwards, thus sepa- 

 rating it from the fingers. 



2. Flexor ossis metacarpi, or opponens polli- 

 cis (trapezo-metacarpien, Cruveilh.), of a 

 rhomboidal form ; it arises from the trapezium, 

 and from the fore part of the anterior annular 

 ligament, anterior to the sheath for the radial 

 flexor of the wrist, by long aponeurotic fibres ; 

 and posteriorly from a septum between it and 

 the short flexor. From these attachments the 

 fleshy fibres radiate downwards and outwards, 

 being so much the shorter the higher and the 

 more transverse they are. They terminate by 



* Soemmering and Albinus divide this into two 

 distinct muscles, the former giving them the names 

 abductores breves pollicis manus interior et exterior ; 

 the latter calls the internal portion abductor brevis 

 alter. 



