. A manual of diseases of the nervous system. e forwards and inwards (flexing the first phalanx), incline itoutwards, and rotate it inwards, so as to place its palmar aspect opposite thefingers. The second phalanx is ultimately extended. If the metacarpal boneis previously abducted the movement is greatei, and amounts to circumduction.(2) The adductor and inner part of short flexor (ulnar nerve—0. 8 and D. 1)go to the inner side of the first phalanx. The metacarpal bone is movedtowards that of the second finger: if previously flexed, it is extended; if pre-viously opposed to the index, it is m
. A manual of diseases of the nervous system. e forwards and inwards (flexing the first phalanx), incline itoutwards, and rotate it inwards, so as to place its palmar aspect opposite thefingers. The second phalanx is ultimately extended. If the metacarpal boneis previously abducted the movement is greatei, and amounts to circumduction.(2) The adductor and inner part of short flexor (ulnar nerve—0. 8 and D. 1)go to the inner side of the first phalanx. The metacarpal bone is movedtowards that of the second finger: if previously flexed, it is extended; if pre-viously opposed to the index, it is moved a little outwards. The phalangesfollow the movements of the metacarpal bone, but the flrst is slightly flexedand the second is extended, as the fingers are by the interossei. The Opponens pollicis (median nerve—C. 8 and D. 1) flexes the metacarpalbone on the carpus, and abducts it, but this movement is insuflScient to opposethe thumb to the index; the conjoint action of the abductor is necessary (seeabove). Fia. 21. Fia. Fig. 21.—Normal position of the thumb (for compprison with the succeeding figures). Fig. 22.—Position of the hand in long-standing paralysis and wasting of thethenar muscles. Under the influence of the long extensDr the metacarpal bone01 the thumb has been brought into the same position as the other metacarpalbones, being rotated slightly, so that tlie bac-k of the thumb is in the plane ofthe back of the hand, like the hand of .tlie ape. (After Duchenne.) Fig. 23, from another case, shows the same condition, but still greater dis-placement of the metacarpal bone has taken place, from the greater contractionof the extensor. (After Duchenne.) The Flexor longus pollicis (median nerve—C. 7 and 8, and D. 1) flexes thesecond phalanx forcibly and the first feebly. It has no action on the metacarpalbone. It is used in writing (malting a stroke towards the body) and in pickingup a small object, &c. In paralysis this flexion is lost, and with
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