Spinal nerve

“ Schiff has shown that galvanization of a cerebro-spinal nerve causes a dilatation of the blood-vessels in the vicinity, as if the vaso-motor force were overpowered by the excessive stimulation of the controlling nerves. If excessive action of the brain or spinal cord be analogous in its effects to galvanism of a spinal nerve, it might be supposed to cause vaso-motor paralysis and hæmorrhage. ”

“ As you will see by the picture, the spinal nerves, which are given off from the cord in the lower part of the neck and between the shoulder blades, are gathered together into a great loose bundle to form the long nerve-wires needed to supply the shoulders and arms. Those given off from the small of the back just above the hips also run together to form, first a network and then a big single nerve-cord, called the sciatic nerve, which many of you have probably heard of from the frightfully painful disease due to an inflammation of it, called sciatica. ”

“ The dorsal muscles can then be pressed toward the vertebral column and dissected away from the peritoneum. The spinal nerves, lying against the peritoneum, will be exposed and can be followed easily, first to their roots, next ventrally.
The hypobranchial nerve, to which attention was called at the point where it crosses the vagus, is formed by the union of the principal branches of the occipital and first two spinal nerves. The third spinal nerve receives a branch from the second, and itself accompanies the hypobranchial nerve closely without actually becoming a part of it. ”

“ When the spinal cord has been severed in the neck this scratching movement of the hind limb can be elicited with regularity as a spinal reflex by merely rubbing the skin of the side of the neck or shoulder, applying there a weak electric current to the skin. In this reflex the stimulus excites afferent nerves connected with the hairs in the skin and these convey impulses to the spinal centres in the neck or shoulder segments, and these in turn discharge impulses into nerve fibres entirely intraspinal passing backward along the cord to reach motor centres in the hind limb region. ”

“ I expect, in short, to convince most readers that the essential seat of every true neuralgia is the posterior root of the spinal nerve in which the pain is felt, and that the essential condition of the tissue of that nerve-root is atrophy, which is usually non-inflammatory in origin. ”

“ In many cases, as has been remarked before, the pathological process descends into the spinal cord. Here, as in the medulla oblongata, the degeneration is principally confined to the motor centres located in the anterior horns, while the posterior horns, together with the lateral and posterior white columns, remain free from disease. The degree of degeneration taking place in the fibres of the respectively paralyzed muscles also corresponds to that of the elements of the nerve-centres from which they are supplied. ”

“ It is not only at their exit that the spinal nerves thus communicate. The different cords of which each nerve is formed have precisely the same arrangement, as may be easily seen in the great trunks, as in the median, the cubital, the radial and especially the sciatic. By separating the different cords of these nerves, we see that they are not only in apposition longitudinally, but that179 they send numerous filaments to each other. These communications do not resemble those of the arteries, in which there is always continuity between the communicating branches. ”

“ The spinal cord, too, is often affected and becomes unable to respond to the demand for reflex action, as appears from the trembling hands, the staggering legs, the swaying body, and the general muscular uncertainty. All these are varied results of the temporary paralysis of the great nerve centers.
Besides, the sensibility of the nerves is deadened. The inebriate may seize a hot iron and hardly know it, or wound his hand painfully and never feel the injury. The numbness is not of the skin, but of the brain, for the drunken man may be frozen or burned to death without pain. ”

“ The nervous influence is only propagated from the superior to the inferior part, and never in an inverse direction. Cut a nerve in two, its inferior part when irritated will make the subjacent muscles contract; let them do what they will to excite the other, no contraction is produced in the superior muscles; so the spinal marrow divided transversely and pricked above and below, produces no sensible effect but in the second direction. ”

“ Now as we are dealing with the omnipresent nerve principle of animal life, I will tell you this one serious truth, and support it by the fact of observation. To treat the spine, and thereby irritate the spinal cord oftener than once or twice a week will cause the vital assimilation to be perverted, and become the death-producing excretor, by producing the abortion of the living molecules of life, before fully matured, while in the cellular system, which lies immediately under the lymphatics. ”

“ Alterations of sensibility occurring in well-defined areas of the hand, trunk, or extremities, corresponding to the known distribution of nerves, almost always indicates disease of the nerve itself, much more rarely disease in the spinal cord at the origin of the nerve. ”

“ Reverting for a moment to the primitive segmental arrangement which is none the less persistent and important because in the completed human the regularity of contour of the segments has been wholly lost and aberrant organs have moved from their original positions carrying their nerve supply with them, let us first state and then illustrate a general law.
Any violence applied to the body tends to affect the spinal column. Such violence does or does not produce permanent displacement of a spinal segment according as it does or does not succeed in overcoming the internal resistance. ”

“ Reflex paralyses, which at one time were believed to be the not infrequent result of nerve-irritation and inflammation, affecting from a distance the functions of the spinal cord, have been shown to be the effect of an extension of the lesion of the inflamed nerve to the cord, causing organic disease. ”

“ A careful examination will discover not only the great rigidity of the spine, and as it were fusion en masse of its joints, but in these persons the bony outgrowths may be felt. Occasionally the alteration in the vertebræ by compressing the cord or its membranes, or the spinal nerves and ganglia, may produce neuralgic pains in the cervical, dorsal, lumbar, or sciatic nerves, wasting of the muscles, more or less paralysis, and even vasomotor disturbances. ”

“ They dwindle in size; they do not, however, die. Similarly, when the axons of the motor spinal cells are by severance of the nerve trunk of a muscle broken through, the muscle cells undergo “degeneration”—dwindle, become fatty, and alter almost beyond recognition. This trophic influence which one neuron exerts upon others, or upon the cells of an extrinsic tissue, such as muscle, is exerted in that direction which is the one normally taken by the natural nerve impulses. ”

“ Many cases of nervous prostration are to be traced not merely to overwork or worry, but to the waste of energy which results from the faulty posture of the body and with the interference of the circulation in the spinal cord, and the consequent weakness of the nerve power which results. ”

“ With a little care it can be stripped off the brain without causing injury to its substance. At the base of the brain the pia mater is prolonged on to the roots of the cranial nerves. This membrane consists of a delicate connective tissue, in which the arteries of the brain and spinal cord ramify and subdivide into small branches before they penetrate the nervous substance, and in which the veins conveying the blood from the nerve centres lie before they open into the blood sinuses of the cranial dura mater and the extradural venus plexus of the spinal canal. ”

“ In relation to the brain, the spinal cord is a great mixed motor and sensory nerve, but, in addition to this, it is also a distinct nervous centre, in which originate and terminate all those involuntary impulses which exert so potent an influence in the preservation and economy of the body. ”

“ According to the Yogis, there are three principal nerve currents: one they call the Idâ, the other the Pingalâ, and the middle one the Sushumnâ, and all these are inside the spinal column. ”

“ The spinal cord, after having frequently performed a certain act under the stimulus of conscious sensation, becomes so accustomed to perform that act that it does it when the oft-felt peripheral impulse comes again to it, although the cerebral functions and consciousness are suspended. A nerve-centre, even of the lowest kind, once moulded by repeated acts, retains their impression—i.e. ”

“ 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. ”

“ Nerve tenderness may be discovered at a little distance from the mid-spinal line and at a level slightly lower than70 the emergence of the nerve. If a nerve is irritated, the finger inserted between the ribs near their articulation with the transverse processes will elicit tenderness. The discovery of tender points along the spine is the most important part of nerve-tracing. ”