Part 42

Finally he must be so cautious and careful in his statements that no doubtful conclusion is allowed to escape from his own mind. We may believe or suspect or hope for proof of our theories but we have no right to state as a fact anything except that which has been proven under the most rigidly guarded scientific test conditions.

Failure to observe any of the precautions mentioned renders worthless the results of investigation. Nothing further than a mere presumption can be based upon research which fails to observe all these rules. It will be readily understood that there are few Chiropractors whose training has been sufficient to enable them successfully to accomplish such research. There are thus many things connected with the spino-organic connections which are commonly held as facts but which should be classed as presumptions. And the prevalence of the habit of general adjustment rather than specific makes the future final solution of all these problems remote.

Kinds of Evidence Acceptable

It will be seen that of the three kinds of evidence--Anatomical, Physiological, and Clinical--which are admissible in reasoning upon the connection between the spine and disease, only one form--clinical evidence--has been adduced by Chiropractic. For anatomical and physiological corroboration of our apparent clinical findings we are obliged to turn to standard works on these subjects; fortunately we find it in abundance.

Anatomy, fortified now by research in the morphologic relations of the parts studied and by physiological and pathological experiment which has thrown much light on the proper viewpoints from which to describe structure, contains sufficient data on the nervous system to enable us to explain practically every fact observable in a Chiropractic clinic.

It is true that there are a few statements in the ensuing outlines for which we cannot as yet find the anatomical or physiological proof. But it must be remembered that anatomists and physiologists have never studied the body with a knowledge of the subluxation theory to aid them in gaining perspective and that Chiropractors, as a class, have not yet delved deeply enough into anatomy and physiology to extract all the available and illuminating information from them. Ofttimes the facts we value most are most obscure in the texts because to others they seem least important. But they are there. Armed with information concerning Chiropractic facts it is probable that the scientist of the future will corroborate all of our clinical findings of today and emphasize the rational explanations of them.

In the following tables it has been found best to insert in parentheses the capital letter (P) to call attention to any statement in support of which we have gathered less than all three forms of admissible evidence and which is therefore as yet presumptive. It is well, however, for the practitioner to be careful lest he regard too lightly such presumptive statements. Unless there is very strong and reasonable ground for such presumption or a general belief in its correctness all mention of it is omitted. Those labelled presumptive are merely so indicated because they have not yet been proven and not because they have failed to serve as a convenient and useful guide to adjustment. For each presumption offered there is either clinical or anatomical justification but not both.

SPECIAL NERVE CONNECTIONS

This section does not purport to state with any degree of completeness the various nerve-paths by which spinal vertebrae come into relation with all, or nearly all, the peripheral organs of the body. It merely points out some of the more interesting and important connections, some of the paths which serve to explain the common effects of vertebral adjustment. It is not expected that this resume of the subject will be more than suggestive to the student; certainly it cannot, in so brief a space, be a complete exposition.

Outline of Nerve System

Let us begin with the observation that almost every organ of the body, including the central nerve organs themselves, may be adversely affected by spinal subluxation impinging spinal nerve axons at their exit from, or entrance through, intervertebral foramina, or by spinal subluxation producing direct impingement upon some part of the sympathetic system and similarly interfering with its power to functionate.

The Nerve System may be divided into two great divisions, the central axis and the peripheral system which distributes nerve energy from, and brings stimuli to, the central axis. The central axis consists of the brain and spinal cord; the peripheral system of 12 pairs of nerves attached to the brain and having exit (except the eighth) through foramina in the base of the cranium, 31 pairs of spinal nerves emerging through intervertebral foramina whose parts are movable upon each other (except the foramina for sacral and coccygeal nerves), and an intricate system of sympathetic fibres and ganglia arranged in a double chain of ganglia in front and at the sides of the vertebral column, three great prevertebral plexuses, the cardiac, coeliac, and hypogastric, and numerous scattered ganglia and communicating cords which bind the ganglia together and connect them with spinal or cranial nerves and with the periphery.

The peripheral system is somewhat complex and numerous intercommunications are established by which nerve impulses originating in the central axis and leaving by one part of the peripheral system may exercise a controlling influence over another part. Plexuses, or intertwinings of nerve axons, are so numerous and complicated that it is difficult to follow each set of nerve stimuli from their origin to their final destination and effect without considerable study.

Direct Distribution of Spinal Axons

The spinal nerve axons, taken as a whole, establish paths between the motor gray of the ventral horn of the spinal cord and all voluntary muscles of the body below the head except the trapezius and sternomastoid, partially innervated by the eleventh cranial, and between the sensor cells of the dorsal spinal gray and gracile and cuneate nuclei of the medulla on the one hand and the sensor end organs in skin and mucuous membrane, muscles, tendons, and joints on the other. The ventral cornu receives impulses from the cortico-spinal axons of the direct pyramidal, crossed pyramidal, rubrospinal, and other smaller tracts which bring the spinal gray under the direct voluntary domination of the volitional centers in the brain or of the indirectly voluntary pathway through the cerebellum. The spinal nerves are the direct media for motion of the body or its parts in relation to its environment. The sensor gray of the cord is similarly in communication with the conscious sensation area in the cerebrum and with the cerebellum by way of the dorsal tracts of the cord, the lemnisci, and the cerebellar peduncles.

In the main these nerves of motion and sensation are arranged as follows:

The Cervical plexus is composed of the intertwining of axons from the anterior primary divisions of the four upper Cervical nerves. Its branches pass to and innervate many voluntary muscles of the neck and side and back of head, and supply sensor fibres to the adjacent cutaneous areas. Branches also communicate with the last three cranial nerves and one long branch, the Phrenic, or Internal Respiratory Nerve of Bell, passes through the neck and thorax to the diaphragm, as its motor nerve.

The Brachial plexus is made up of the anterior primary divisions of the four lower Cervical nerves and the greater part of the first Thoracic. It is distributed chiefly to the voluntary muscles and integument of the shoulder and arm, forearm, and hand, but sends branches to some muscles of the neck and upper back as well. It, like the Cervical plexus, receives branches from, but gives none to, the Cervical sympathetic.

The Thoracic nerves are not arranged in plexiform fashion like those above but pass separately, for the most part, to their destinations. They are distributed to the walls of the thorax and abdomen following the curve of the ribs in direction. The last Thoracic sends one division downward as far as the outer aspect of the ilium.

The Lumbar, Sacral, and Pudendal plexuses are formed of the ventral divisions of the Lumbar, Sacral, and Coccygeal nerves and distribute branches to the integument and voluntary muscles of the lower abdomen, pelvis, and lower extremities. From two of the sacral nerves branches known as “Visceral” pass through the plexus to terminate in the walls of the uterus and rectum.

All of the thoracic nerves and the first and second, sometimes the third and fourth, lumbar give off branches to the sympathetic ganglia, known as white rami communicantes.

Direct Distribution of Cranial Nerves

The distribution of the 12 pairs of cranial nerves is not so definitely to voluntary muscles and to areas from which conscious sensation is to be derived as is the case with the spinal, although the cranial nerves present many analogies with the spinal and there is abundant reason for considering them as in one series of 43 pairs. There is direct distribution of some cranial nerve fibres to secreting glands, but these fibres are probably merely derived from sympathetic trunks and carried in company with the axons of cranial origin. There is also some direct distribution of cranial nerve axons to visceral walls made of non-striated muscle, as in the case of the vagus distribution to the respiratory and alimentary tracts and that of the spinal accessory to the heart. This is a resemblance to the sympathetic.

The cranial nerves carry afferent impressions from the special sense organs, except those of the sense of touch, which function is divided with the spinal nerves.

Various intercommunications exist between the cranial and sympathetic divisions of the peripheral system, by means of which axons starting with one division may be finally distributed with another, or by which an axon of the sympathetic may pass to one of the sensor ganglia of the cranial system and influence its nutrition and condition, and therefore its power to act. There is a limited intermingling of spinal fibres with the lower cranial.

Distribution of Sympathetic

The sympathetic system directly innervates most of the nutritive or vegetative system, the alimentary tract and its accessory organs, the vascular systems, the genito-urinary system, and the ductless glands. To a limited degree it shares this control with the cerebro-spinal and to a much greater degree it brings the central axis into indirect connection with these viscera.

Gray says, “The distinction of the sympathetic system from the cerebrospinal system is made merely for reasons of convenience. The two systems are intimately connected and the sympathetic is morphologically a derivative of the central axis disseminated in connection with the nutritive apparatus and establishing relationships among the vegetative organs.”