Page:Popular Science Monthly Volume 20.djvu/606

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588
THE POPULAR SCIENCE MONTHLY.

either flexed or kept straight. The thumb is simply extended backward, and somewhat abducted from the fingers; and a twitching of the fingers is frequently observed.

The energetic or powerful hand is the reverse of this, and is probably seen in life only under certain conditions of the mind, producing what we call "mental states," or states giving energy and the feeling of strength.

The most natural position of the hand is that of rest, and here analysis shows all the joints in flexion. The hand may be seen in perfect rest during sleep, or when the man is resting, engaged in quiet, unexciting conversation.

The antithesis of this is a hand in general extension or ortho-extension. The term ortho-extension is used to imply that the joint is so far extended as to place both the bones constituting the joint in the same straight line. If extension be full or complete, the bones form an obtuse angle with each other.

In the "ortho-extended hand," the axes of the metacarpal bones (hand-bones) and of the digits are in the same plane with the bones of the fore-arm, and the position is represented in which a strong man naturally holds out his hand when requested to put it forward. A healthy child, when it runs in its play or to meet a friend, commonly holds out its arms, the hands assuming the "energetic position"; and this, as the result of observation, is, I think, characteristic of a healthy, nerve-muscular condition; healthful children in pictures by the best masters are often thus represented. When a child is in a state of convulsion it is well known that usually the hand is closed, with the thumb turned in upon the palm, the fingers being flexed around it. Such a position of the band in a child when ill is very indicative of a state of the nervous system predisposed to convulsions.

Equally characteristic with the passive positions of the hands are the muscular movements of the fingers—twitching, tremors, and rhythmical movements. These conditions have been more fully studied and described than the characteristic passive positions (postures), and they have long been considered as visible muscular conditions expressive of the states of the nerve-centers. The varieties of finger-twitching may be described as—1. Flexor-extensor, the primary movement being that of flexion, followed by a secondary extension movement. This may be seen in a variety of cases, and in particular is seen in what is called "picking the bedclothes" in the typhoid state preceding fully developed coma. 2. Extensor-flexor, the primary movement being that of extension, followed by a secondary flexor movement. This is common in the slighter forms of chorea and in nervous children; such twitches usually constitute the subsultus tendinum' so indicative of exhaustion in the course of typhoid fever. 3. Abductor-adductor twitches, the movements consisting in lateral separations of the fingers, followed by their being drawn together again.