STIMULATION OR INHIBITION.
We can produce stimulation or inhibition of a nerve at will; press suddenly and with a little violence upon the ulnar nerve where it lies in relation with the internal condyle of the humerus and we will find a manifestation of its physiological action, evidenced by a sense of pain in the ulnar and radial sides of the fifth finger and the ulnar side of the fourth, together with contraction of the muscles supplied by that nerve. But if our pressure be less intense and more prolonged we will inhibit the nerve and produce a sense of numbness in the same area together with temporary loss of muscular control.
Osteopaths well understand how to produce either stimulation or inhibition of the ganglia by way of the nerves passing to them from the spinal cord, and the results of such inhibition or stimulation in any sympathetic area can be prophesied readily by anyone who has read with attention what I have written; for instance, in the case of inhibition in the region of the nerves supplying the superior cervical ganglion with nerve force, we will find, first, throughout the area of distribution of the branches of this ganglion a relaxation of the vascular walls. This will be marked by two indications, first, the skin will become flushed and moist; second salivary secretion and lachrymal secretion will be increased. Second, the vagus is now allowed full sway, and we will find slowing of the heartbeat. It is well known that pressure over the seat of the first spinal nerve for a very brief period of time will control a congestive headache; the pressure in such case is made only for so long time as to produce stimulation of the sympathetic to greater activity, when we will attain a vaso-constrictor action, lessen the volume of blood in the cranial cavity and so abolish the headache. The arteries of the body may be divided into three groups, the large, the medium-sized and the small; in the first of these we find little muscular tissue and much elastic; in the second they exist in about equal proportions, while in the small arteries we find much muscular tissue and little elastic. As a consequence it is upon the smaller arteries that the sympathetic system has its greatest effect. As we dilate the smaller arteries and slow the heart action, it follows that we reduce the blood pressure, as we reduce blood pressure we reduce temperature, and within a very few minutes after the commencement of this inhibitory pressure on the upper four cervical nerves we will find in the large majority of cases, the capillaries over the entire surface of the body flushed, this being accompanied by a fall in the pulse rate and a marked diminution of the temperature. Indirectly at the same time we produce an effect upon the lungs; as we lessen blood pressure and the frequency of the heart action we find in accordance with the physiological rule an alteration in the respiration, it becomes slower and deeper. Arguing along these lines, and applying similar reasoning to each of the branches of this ganglion, anyone can trace out the many subsidiary results which may be expected from either stimulation of the rami communicantes nerves distributed to it, or their inhibition. Exactly similar rulings will find their prompt proof with regard to any other of the ganglia of the sympathetic system. We will find corresponding results in the cases of the thoracic ganglia which form by their branches the pulmonic plexuses; we get the same results from the splanchnic ganglia; while in the lumbar region we find that we have a ready means of control of the vascular system in the lower abdomen and pelvis. Much, very much, is still to be learned concerning the sympathetic nervous system, and all such increase in knowledge can come in one way only, clinical observation of Osteopathic treatment.
William Smith,
L. R. C. P. and S., (Edin.), D. O.
THE END.
FOOTNOTES
[1] Explore: (1) To seek for or after: to strive to attain by search; to look wisely and carefully for; to search through or into; to penetrate or range over for discovery; to examine thoroughly; as, to explore new countries or seas; to explore the depths of science; "hidden frauds (to) explore."—Webster.
[2] Chambers.
[3] "The secretion of the external auditory meatus, mixed with the secretion of the neighboring glands or ceruminous glands, forms the well known ear-wax or cerumen. The secretion in this place contains a reddish pigment of a bitterish sweet taste, the composition of which has not been investigated." American Text-Book of Physiology.
[4] Chambers.