Part 16

It is well known that by placing an elbow firmly against a man’s jaw and then sharply striking the closed fist with the other hand, open, a very heavy blow can be given; yet the forearm, through which the shock is transmitted, does not move.

Now ivory is very like human bone. Further, it has been demonstrated that the law illustrated by the above experiment is equally applicable to the movement of vertebrae. The pushing or thrusting movement may move a specific vertebra, but it is probable that the chief factor in so doing is the element of transmitted shock contained in the movement and delivered at the instant of release of the hand from the spine at the end of the movement.

On the other hand it is obvious that a pushing or thrusting movement may move several vertebrae in addition to the one directly in contact with the adjusting hand, in consequence of the way in which the spinal segments are closely bound together. If a steady strain is used, in which muscles and ligaments have time to act, one of three results may occur: (a) the specific adjustment; (b) the movement of several vertebrae at one time, which does not constitute an adjustment; (c) the giving way of the spine at its weakest point, which may be some distance from the point of contact with the adjusting hand, the ligaments and muscles having communicated and diffused the strain throughout a large area. In the latter contingency the result is usually a new subluxation or the increase of an old one, instead of an adjustment.

The Rapid Movement

Thus Speed becomes an important factor in correct adjustment.

A good illustration of the value of speed may be taken from a pile of stakes bound together by a cord. If a man with a hammer desires to remove the center stake of the group, and attempts to do so with a slow pushing movement, the result is a change of position of many stakes, which adhere to the center stake and to each other. If, on the contrary, he strikes a sharp, quick blow with his hammer, meeting squarely the center of balance of the one stake, it will fly straight from its position leaving the others unmoved. This is exactly what we desire to accomplish with an adjustment. By the speed of the movement we expect to move one vertebra before adhesion or the contraction of muscles or inelasticity of ligaments can diffuse the force.

Close Contact

In order to accomplish the transmitted shock it would seem wisest, at first thought, to draw back the hand and strike the vertebra sharply. On the contrary, it has been found advisable to place the hand carefully in close and immediate contact with the vertebra to be adjusted. Nature herself shows us the way in the delicate shock-transmitting mechanism of the tympanum.

Also the hand of the adjuster will cover much more than merely the spinous or transverse process which is used as a lever and to which it is desired to transmit the shock, unless carefully placed so that only a small portion is in contact; by such a contact diffusion of the shock is prevented and its efficiency within a limited area is increased. A carpenter wishing to countersink a nail places in contact with the nail head a small instrument called a countersink, which he then strikes sharply with a hammer. The contact hand of the adjuster represents the countersink and is used by the two arms as a passive instrument for transmitting shock.

The close contact of the hand, which remains passive, renders the adjustment much less painful to the patient than it would otherwise be, and one of the prime objects in the mind of the adjuster should be the minimizing of pain inflicted, by any means which does not lessen the resulting benefit. Also any drawing back of the hand before the movement warns the patient and tends to induce involuntary muscular contraction which interferes with adjustment.

Relaxation

In an adjustment it is necessary to overcome two kinds of resistance--the passive resistance of inertia, of ligaments, or of superincumbent weight, and the active resistance of muscular contraction. It is important that both forms be minimized.

The first may be lessened through the position of the patient’s body; he is placed so that the vertebra to be adjusted is in the freest possible position. The second is reduced to the least possible quantity, amounting to no more than muscle tonus, by using two methods: (a) Oral Suggestion, and (b) Muscular Suggestion.

Oral Suggestion

Explain to the patient the need for relaxation. Make it clear to him that less force will be required if his muscles are passive. Remind him frequently of this and assume that he desires to relax. A word immediately before the adjustment often induces a temporary relaxation during which the adjustment is given. Anything which detracts the attention from the coming shock is an aid. Sometimes asking the patient to inhale and exhale slowly and deeply will sufficiently take his attention from the adjustment. Experience will teach him that he suffers less pain when relaxed and presently relaxation becomes a habit. Instructing patients to think of sleep, turning the eyeballs upward, has been effective with some.

Muscular Suggestion

This can only be given by maintaining a state of relaxation in one’s own muscles, which in itself is desirable in most cases, for reasons to be presently explained. In handling Cervical vertebrae move the head gently from side to side with your own hands relaxed as much as possible. The lazy motion suggests relaxation. Then when it is felt that the neck is thoroughly relaxed, vary the motion with a quick adjusting movement.

In Dorsal and Lumbar regions after the hands are in correct position the adjuster should pause a moment both to be sure that the direction of movement and his purpose to move are clearly fixed in his mind and to be certain that both himself and the patient are relaxed. The adjustment is given instantly and from a perfectly lax muscle, as a boxer strikes.

An added advantage is the greater amount of speed and control which may be commanded in this way. The lax arm, being in a neutral state as regards motion, can be contracted in any desired direction without loss of force or of time, whereas a taut muscle cannot further effect motion of the arm without relaxation of its antagonistic muscles, which takes time.

Muscular Control

Considerable contral over one’s own muscles is necessary in order perfectly to relax arm and shoulder muscles just before the adjustment and then to utilize a measured and determined quantity of force in a desired direction. To acquire this much practice is necessary--practice on the living subject. The desired end may be hastened, however, by acquiring the abstract property of muscular control or by developing control already gained.

Many different forms of exercise will aid in the acquisition of muscular control and the ability to relax and then to follow the relaxation with an instantaneous whiplike contraction in a given direction. The best of these is without doubt bag-punching. The movements employed with a punching-bag, especially the lateral quadruple movement with both elbows and both hands, tend to develop precisely the sort of control needed for correct adjusting. The beginner can do no better than to practice in this way, by which, it must be remembered, only a necessary property, and not by any means the exact movement, may be acquired.

Amount of Force

The amount of force used in an adjustment varies so much in different spines and in different parts of the same spine that it is quite impossible to state any correct estimate of it in terms of physical units. In general the Cervicals move with least resistance, then the Dorsals, then the Lumbars, and finally the Sacrum and Ilia as hardest of all to displace or replace.

In developing additional force when it is found that the force first used on any vertebra has been insufficient to move it, remember this law: Work equals one-half Mass times the square of the Velocity. In other words, doubling the speed of the movement increases its effectiveness four-fold; tripling it, nine-fold.

The increase in force should never be effected by increasing the weight or pressure upon the patient’s body, for reasons which should be clear from a study of previous pages, but always by increasing the speed of the movement.

Names Used to Describe Movements

The names herein employed to indicate certain movements, each a well-defined method of procedure for the accomplishment of some special end, are the names or descriptive terms which seem to be in the most general use at this time. Few of these movements have arrived suddenly; most of them are the result of gradual growth and evolution: so with the terms by which they are known; they have gradually become a part of the common language of the profession. Usage sanctions them, though some of them are cumbersome, unwieldy, or entirely inappropriate.