A movable joint is a means whereby two neighbouring parts of the human body are kept in approximation while at the same time these parts are kept apart. The parts are kept in approximation by ligaments and by the tension of muscles. The parts are kept apart by cartilage and by synovial fluid bounded by a closed membrane. Mechanically a joint is a "bearing" whereby one part rides upon another. The function of the ligaments is to limit disintegration between the parts. The function of the muscles intrinsic to the joint is to provide a constantly adjusting form of guidance for the moving part upon the stationary part. For each joint there is a range of excursion for the moving part. This excursion is limited by the length and nature of the ligaments and the contractile and expansive capacity of the muscles concerned. Within the possible excursion there is a point which may be described as neutral within that excursion where the part is neither moving this way nor that way in any plane. When that point is maintained by the tonic action of the muscles concerned with the formation of the function of the joint, then the just function of the opposing factors within the joint is determined. The contents of the joint are cartilage and the closed chamber of synovial fluid. These combined have an elastic quality. Thus when the moving part is at the neutral point of its excursion the thrust of the elastic property of the joint is "true" through the axis of the joint.

Now, if in the living subject the experience of the "neutral point" could be communicated to the subject and learned by the subject as an experience in proprioceptive sensation, then the subject would have at his command a means whereby he could maintain the corresponding measure of muscular tension while the moving part made its full excursion. If this neutral point could be determined for all movable joints then the subject would be in a complete state of equipoise so long as the neutral point was maintained. That is to say that while at all joints the muscles concerned with the formation of the functions of these joints would be in a state of tonic contraction no excursion of the moving parts in any possible direction would be taking place. It is obvious that if the point of neutrality was exhibited in use in all joints at one time then the muscular tension would be minimal and uniform throughout the whole muscular system.

The creation of such an order of equipoise throughout all the movable joints demands that there is a joint which is primary in this order. It can be demonstrated that to create equipoise throughout all the joints, the first joints at which equipoise must be established and maintained are the atlanto-occipital joints, which may be considered as one joint in two parts. The reason for this selection is that this joint is central and that the "thrust" is freely upwards into space.

The state of muscular tension which is required to maintain equipoise at all joints is a desirable constant and should continue always to prevail while movements at joints take place.

It might be assumed that this constant would be an inherent property of living beings, but it can be demonstrated that in practically all human beings no such constant in fact prevails, and that, generally, all human beings constantly exhibit a departure from the use of equipoise in their daily lives. Human beings have depended upon instinctive or habitual guidance of the mechanism producing equipoise at the atlanto-occipital joint, and habitual guidance has resulted in constant deviation from the use of equipoise at that joint. Flowing from this habitual manner of guidance comes a defective proprioceptive mechanism. For the standard of the experience of equipoise is never known and so no aberration can be recognised. By constant deviation from the use of equipoise at the atlanto-occipital joint structural and functional abnormalities occur at innumerable places. By failure to exercise equipoise the subject is always in a state of bias, and therefrom judgments are warped and faulty. This very bias has been the means whereby the importance of functioning at the atlanto-occipital joint has been disregarded by investigators in anatomy, physiology, and in the application of these studies to practical medicine.

The list of advantages which could be shown to flow from the establishment of the use of equipoise at the atlanto-occipital joint could be shown to be lengthy and comprehensive. To render that use conscious and constant would be to make the list of advantages endless. Among these advantages would be numbered, a knowledge of the means whereby the upright "posture" could be maintained; a knowledge of how to use the self so that perfect functioning would always be the rule in all activities; a constant improvement in kinaesthetic accuracy with all that that connotes; and optimum functioning in all intrinsic functioning such as breathing and digestion. In addition, by the constant projection of the experience of equipoise at the atlanto-occipital joint the human being is integrated, appreciates the importance of integration, and develops the faculty of considering all factors in a situation rather than discrete and specific factors.

We have to thank the worker, F. Matthias Alexander, for the discovery that equipoise can be established at the atlanto-occipital joint, that it can be learned as a proprioceptive experience, and that the experience can be projected constantly and consciously. A description of the manner of his discoveries is contained in his book The Use of the Self. Details of the technique of the application of his discoveries to human beings in the use of themselves is contained in his other books, Man's Supreme Inheritance, Constructive Conscious Control of the Individual, and in his newest book, The Universal Constant in Living. These books should be read by every layman as well as by every investigator in the anatomy and physiology of the living human being if they desire to have new vistas of experience opened to them.

Mungo Douglas, M.B.,
134, Ainsworth Lane, Bolton, Lancs., England.
8th August, 1942.