Part 13

Care should be taken that equal pressure be made on all points palpated on one nerve. If the nerve pass over a bone, less force is needed to exert the same pressure than if it overlie muscle or other soft structure. The force used varies constantly as the hand moves from place to place, according to the density and hardness of the structures overlying and underlying a nerve.

Sufficiently heavy pressure will elicit tenderness in all except anaesthetic patients. But if a nerve be irritated it will be tender without heavy pressure, when the finger really makes a close contact with it.

If the patient willfully attempts to deceive the palpater, nerve-tracing might as well be abandoned except in those extreme cases where the patient will flinch against his will on account of extreme sensitiveness.

Use of Second Hand

As far as possible, the second hand is placed opposite the tracing hand and steadily supports the body; its position changes with changes in the position of the first. If the arm is to be examined it had best be held away from the body, and the part to be examined held between the two hands.

Position of Patient

For tracing nerves in the neck, back, and upper extremities, the patient should sit easily. For lumbar, abdominal, or pelvic tracing, or for tracing in the lower extremities, have patient lie on side or back. Do not hesitate to change the position of the patient as often as is necessary to secure easy access to the part to be examined and relaxation of the patient’s muscles. Never allow the assumption of a strained position during tracing; the sensation of cramped muscles may be confused with sensations of nerve tenderness.

SUBLUXATIONS

Definition

A vertebral subluxation is a displacement, less than a dislocation, in which the chief element is the partial loss of normal apposition of the articular surfaces of the subluxated vertebra with those of the vertebra above or below, or both. Or, Vertebral subluxation is a permanent partial dislocation.

How Produced

Subluxations are primarily caused by trauma--falls, blows, strains, etc., being the chief factors. Hereditary weakness in structure of some part predisposes by rendering that portion more easily displaced.

Subluxations are never hereditary but may be congenital through violent or instrumental delivery into the world or may appear hereditary because they occur shortly after birth through the effect of light jars upon the hereditarily weakened segments of the spinal column.

They are always the result of concussions of forces; never of forces acting entirely within the organism. They result from the contact of the body with its environment.

It has been said that muscular action in response to peripheral irritation may produce subluxation. The laws of reflex action render this impossible. Given a normally aligned vertebra, and consequently normal nerves and a normal reflex arc in that segment, the ventral horn cells respond to a slight peripheral stimulus by exciting muscular contraction on the same side with the irritation. If the irritation be sufficiently increased, the response occurs on both sides but most strongly on the side from which the irritation comes. Greater irritation merely serves to cause greater distribution of the responsive action. (See any standard physiology on reflex action.) In no case will the difference between the contractions of muscles on the two sides be sufficient to displace a normally aligned vertebra. Nature has provided against that contingency.

Given a subluxated vertebra causing nerve impingement and thus interruption of the normal action of the reflex arc, irritation may result in greater contraction upon the opposite side than upon the side of the irritation. This is an abnormal condition and accounts for the increase of previously existing subluxations under pain or peripheral irritation. But in every instance trauma must and does precede and cause subluxation.

Reaction of Secondary Causes

Once produced, however, a subluxation may not cause noticeable effect until it has been increased in degree by the reaction of forces within the body such as poisons, general fever, etc. Thus germs, dietetic errors, exposure to sudden temperature changes, waste of energy through abnormal mental activities, as hate, fear, worry, etc., or through physical excess--in fact, all the secondary causes of disease may appear to have produced a subluxation. In fact, they have merely accentuated that which already existed and have done so through the muscular contractions which they induced.

General thinning of intervertebral substance through a condition of disturbed metabolism itself produced through the agency of some one serious subluxation, may narrow all the foramina and increase impingement of nerves at any point where a slight subluxation previously existed. An irritated nerve may become swollen and the nerve impinged at the foramen.

Law Governing Location

So definite is the law governing the effect of force applied to a given portion of the body upon an associated vertebral segment that the skilled Chiropractor who has studied vertebrate segmentation thoroughly may determine, from the history of a fall or injury, the vertebra which would tend to be subluxated by that injury and the tissues controlled from that part. The rule is this:

Force applied to any body segment tends to subluxate the segmentally associated vertebra. This subluxation tends to produce disease throughout the area of distribution of the subjacent pair of spinal nerves.

The task of explaining this law seems hopeless unless the student is familiar with human embryology and the life history of the vertebrata, as well all the details of human anatomy. To such a student the law will be self-evident, so interwoven with the threads of higher organization as practically to form its pattern.

In simple terms we might offer this general statement. Any force applied to the body with sufficient violence will produce subluxation of the vertebra above the spinal nerves supplying the injured area. Thus, the brachial plexus controls the arm and shoulder and connects with the spine by way of the 5, 6, 7, 8, Cervical and 1 Dorsal nerves. Any force striking the arm or shoulder tends to produce subluxation of the sixth or seventh Cervical or first Dorsal vertebra so that all permanent disease conditions resulting will be found in the arm or shoulder or nearby tissues of the neck.

This theme presents a magnificent field for individual study and research but is, per se, beyond the limitations set for this work.

Effect of Subluxations

Slight subluxations may exist, because of the adaptation of surrounding parts and the slight play within the intervertebral foramen, without producing noticeable effect. They always, however, evidence a tendency to disease.

The majority of subluxations do produce disease, to some degree, and do so by impinging nerves. Impingement may be either by pressure against a nerve or ganglion or by constriction of a nerve where it passes through an intervertebral foramen; the former occurs in the case of the Cervical sympathetic, the sub-occipital nerves, and the sacral nerves; the latter is the commoner form in Dorsal and Lumbar regions of the spine. Probably the most positive constriction of a nerve which can occur within the body is to be found in rotation of Lumbar vertebrae; the body of the rotated vertebra encroaches upon the inferior nerve on the side opposite to the direction taken by the spinous process.