It has been said in a previous section that when subluxation and disease are associated the subluxation always precedes the disease and that the former is the cause, the latter the effect. So clearly do we understand this law that we are able to say what subluxation would cause a certain disease and err by only so many cases per centum as there are variations from the usual structure of the spinal column and the nervous system.
But merely to state that a second Dorsal subluxation causes heart disease is not enough. We must know why and how it causes heart disease and whether, perchance, some other subluxation may sometimes have a like effect. We must map out the sphere of malign influence of each possible subluxation so that when our fingers encounter it it at once and inevitably suggests its possible effects, from which, by diagnostic methods, we may choose the one toward which most symptoms point. And we must know the relation of every nerve in the body to peripheral organs and their functions so that when we encounter indubitable evidence of some functional or organic disease we may know exactly where, in the spinal column, to seek for its cause.
We have learned how to discover a subluxation, how to adjust it, and how that adjustment permits a natural cure of its abnormal effects. We must now learn exactly where to apply adjustment for any given organ in the body or for any disease. It must be understood in interpreting this statement and all those which follow in this section that it is never proper to adjust a vertebra merely because it is stated to be the cause of a disease believed to exist in a patient. No vertebra should be moved unless palpation determines it to be subluxated. Rather let it be known that as a rule the statements of spino-organic connection here made will prove to be verifiable by palpation. There is no rule in Chiropractic without some exceptions, and mere diagnosis of disease is too notoriously unreliable to serve as a guide to adjustment without the verification of the trained touch.
The Field of Study
We wish to know the relation existing between each part of the Nerve System and other parts and between each part and the other organs of the body. Especially we wish to understand the relation between each part of the Nerve System and the spinal column, by which permanent subluxations of the latter interfere with the former’s action and therefore with the peripheral organs.
This requires a general knowledge of anatomy, physiology, and pathology which we shall presuppose the reader to possesses so that we may present only facts to which his attention should be particularly called. Let us begin with the relation of nerve tissue to other tissues where this relation can be most clearly comprehended, namely, with the development of the human embryo.
Segmentation
The complete human organism represents the snarled fusion of a series of similar, yet specialized, somatic segments, each presenting most of the attributes of a simple animal, though the association and co-ordination of all are required for the production of higher animal phenomena.
The embryo is composed of such segments placed with their centers in the same axial line. Each segment contains in association which is morphologic, physiologic, and anatomical, a segment of nerve matter and a somatic (body) segment. The neural segments are arranged end to end so as to form the rudimentary beginning of the complete central nerve axis of the adult human body; the somatic segments blend together with somewhat indefinite lines of cleavage which are to become much more indefinite and obscure by changes in relative form due to differences in the growth rate of different parts or to involuntionary changes following functional inutility at various periods. Gray says, “The intrinsically segmental nature of the spinal cord is expressed by the association of each definite segment with the somatic segment supplied by its nerve.”
Within each segment there may be observed at an early period cell migrations from the walls of the primitive neural tube and amoeboid projection of axonic and dendritic processes from these cells, which serve to bring the other tissues of the segment under the control of the nerve elements; there is an assumption of command, as it were, by the nervous system, so that the epithelial, connective, and muscular tissues of each segment are linked in sensomotor and vegetative co-ordination by the contact association of the nerves which ramify them—sensomotor because the nerves are presently to carry the only force capable of inciting activity of any kind in other tissues, vegetative because the functions of growth, nutrition, and repair, in each somatic cell, depend upon the continuity of communication between it and the lowest nerve cell in the nerve pathway which connects it with the higher motor and sensor centers.
Development of the Nerve System
Already may be noted a hint and a prophecy of that future segmental organization by which it becomes possible for some spinal vertebra to become displaced and thus begin a morbid process which may diffuse itself throughout an entire body segment, involving neural and somatic elements together. Already the simple organization begins to become rapidly complex and difficult to trace.
Cell masses begin to migrate from the walls of the primitive neural tube to a position laterad to become the spinal ganglia; these send out long dendritic processes which marvellously thread their way to a predetermined peripheral connection which is to bring some cutaneous, or muscular, or joint tissue into sensor relation with the dorsal, or Sensor, portion of the cord and through it with the brain; at the same time they send their axonic processes inward to mingle with and communicate with the dendrites of other sensor cells remaining in the central axis to form the gray matter of the cord, and thus, migrating, keep up communication both with the central axis and the periphery. Other cell masses migrate ventrolaterad to form the sympathetic ganglia and they also send out afferent and efferent processes which make a connection on the one hand with the periphery and on the other with the source from which the cells developed, the situation to be occupied by the cord. From this view it is seen that the sympathetic system is merely an offshoot from the same source with all the rest of the peripheral nerve system, merely a mechanism for the proper distribution of nerve impulses from the central organs, and that it retains its connection in all its parts with those organs. Its ganglia, like those of the cord, are always and from the beginning under the domination of the upper or cephalic end of the neural tube.
This cephalic end rapidly expands. Its growth ...