Nerve force

“ In other words, the supply of nerve-force being ample, the cells will energize pleasantly: when the nerve-force is insufficiently produced, or by action is exhausted, the energizing will be attended with proportionate pain. ”

“ This brings me to the consideration of another point, namely, that violent stimulation of a centre exhausts the nerve-force, not of that centre only, but of the whole nervous system. A terrible shock may so use up the nerve-force that the individual falls senseless, or, short of this, he may yet be so paralyzed with fear or grief that he loses all muscular power, or he may be so violently moved that the great exertions which he makes only last for a short time. ”

“ On all sides the idea of nerves deriving their power from another source than their own substance is seen to be untenable. A priori this might have been concluded. Neurility is the vital property of nerve-tissue. “Nerve-force” is nerve-action—molecular changes in the nerve itself, not in some remote substance. That nerve and centre are vitally connected is true; and what their physiological relations are will hereafter be examined; but we must dismiss the idea of nerves having the relation to centres that electrodes have to batteries. ”

“ Experience seems to teach that in those patients whose brains have been so weakened by long-continued peripheral excitement, causing frequent and increasing losses of nerve force, there is not sufficient mental power to enable them to control any less powerful irritation of smaller branches of the pudic nerve, than that removed by operation. ”

“ Experience shows that nerve-force is generated and set free whenever the cerebro-spinal system is excited. The direction which this nerve-force follows is necessarily determined by the lines of connection between the nerve-cells, with each other and with various parts of the body. ”

“ By the separation of a main branch of one of the nerves of sensation, although all the operations of life will still proceed, the organ to which that nerve goes is dead to its particular sense. In like manner, if one of the nerves of volition is divided, the member will not obey the inclination of the brain. It is evident, therefore, although many of the great phenomena of vital force are dependent on the nervous system, and the paralysis of a member ensues upon the separation or the disease of a nerve, that the nerves are but the channels through which certain influences are carried. ”

“ DISEASES OF THE NERVES. Most people imagine that nervousness is the result of too much nerve force, but the opposite is the case. The trouble is a too sensitive battery and inadequate nerve force. The batteries, or nerve centres, are too easily discharged. ”

“ The action of nerves, under the pressure of extraordinary influences, may include all manner of vagaries which really have nothing in common with the effects of ordinary functional stimulation; which are, in fact, nothing but perturbation. No one can suppose, for instance, that the explosive disturbances of nerve-force which give rise to the convulsions of tetanus are any mere exaggerated degree of the orderly and symmetrical action by which the healthy nerve responds to the stimulus of volition ordering a given set of muscles to contract ”

“ Still, even upon this dark subject recent research has thrown some gleams of light. A nerve-centre is a place where force is liberated by the lapse of the chemically-unstable nerve-molecules into a state of relative stability. ”

“ It furthermore became clear to me that, though the force resides in all parts of a body, floating in every corpuscle of blood, yet its proper channels of circulation and communication are the nerves, so that as soon as a nerve in any one shape of life touches a nerve in any other, there is an instant tendency to establish in them a common level of the Force of Life. ”

“ Whether a nerve is merely a conductor, which delivers at one of its extremities an impulse received at the other, or whether, as some now think, it is itself a generator of force {56}which is initiated at one extremity and accumulates in its course to the other extremity, are questions which cannot yet be answered. All we know is that agencies capable of working molecular changes in nerves are capable of calling forth from them manifestations of activity. ”

“ Why is there not suffering produced, by the irritation of an insensible part that is at the side of a nerve, or even connected with it, whilst the pain is very acute in an inflamed part, though it is at a distance from every nervous cord? Would the nerves then have also, a sphere of activity for motion? But why should the contiguity of the nerve never be sufficient to produce it in the muscles? ”

“ And it is this readiness of organic tissues to respond to a suitable stimulus that physiologists designate by the term "excitability."
Nerves, no less than muscles, present the property of being excitable. If, together with the excised muscle, there had been removed from the animal's body an attached nerve, every time any part of this nerve is stimulated the attached muscle will contract as before. ”

“ A stimulus applied to a nerveless muscle can only course through the muscle by giving rise to a visible wave of contraction, which spreads in all directions from the seat of disturbance as from a centre. A nerve, on the other hand, conducts the stimulus without sensibly moving or undergoing any change of shape. Now, in order not to forget this distinction, I shall always speak of muscle-fibres as conveying a visible wave of contraction, and of nerve-fibres as conveying an invisible, or molecular, wave of stimulation. ”

“ We must not assume, however, because we see nothing following the irritation of a nerve, that nothing happens. There may be changes in the nerve for all we know to the contrary, and the fact that changes do occur in the nerve would be evident if the nerve had still been connected with a muscle, because then, as you now know, irritation of the nerve would have been followed by contraction of the muscle. ”

“ Continuing his experiments, he proved that there is a nervous circle connecting the muscles with the brain, that one nerve is not capable of transmitting what is called the nervous spirits in two different directions at one instant of time, but that for the regulation of muscular action there is a nerve of sensibility, to convey a sensation of the condition of the muscles to the sensorium, as well as a nerve of motion for conveying the mandate of the will to the muscles. ”

“ At the surface of the body and limbs, the external termini of the nerves are exposed to disturbance by contact with an external object. Along the highly sensitive and minute conductor, the nerve which has by contact with an external object at its outer extremity received a slight shock, there passes through the fluid or semi-fluid substance of the nerve a wave of disturbance, or a succession of such waves. This disturbance reaches the brain, the great nerve-center, where it becomes a feeling. ”

“ We have now presented some evidence that nervous energy is discharged by the adequate stimulation of one or more of the various receptors that have been developed in the course of evolution. In response to an adequate stimulus, the nervous system is integrated for a specific purpose by the stimulated receptor, and but one stimulus at a time has possession of the final common path— the nerve mechanisms for action. The most numerous receptors are those for harmful contact; these are the nociceptors. ”

“ During stimulation, therefore, a nerve exhibits a negative variation. We may express this in a different way by saying that a ‘current of action’ was produced in response to stimulus, and acted in an opposite direction to the current of injury (fig. 2, b) . The action current in the nerve is from the relatively more excited to the relatively less excited. ”

“ One of the most interesting discoveries of physiology was the discovery, made simultaneously in France and Germany fifty years ago, that nerve currents do not only start muscles into action, but may check action already going on or keep it from occurring as it otherwise might. Nerves of arrest were thus distinguished alongside of motor nerves. The pneumogastric nerve, for example, if stimulated, arrests the movements of the heart: the splanchnic nerve arrests those of the intestines, if already begun. ”

“ As motor nerves, when irritated, produce movement, because they are connected with muscles, and glandular nerves secretion, because they lead to glands, so do sensitive nerves, when they are irritated, produce sensation, because they are connected with sensitive organs.... Whether by the irritation of a nerve we produce a muscular movement, a secretion or a sensation depends upon whether we are handling a motor, a glandular, or a sensitive nerve, and not at all upon what means of irritation we may use. ”

“ All the operations of the nervous system are performed by the influence of the nervous fluid, which is generated in the gray portions of the brain and ganglia. Whenever a nerve is cut off from its connection with these nervous centres, its power is gone, and the part to which it ministered becomes lifeless and incapable of motion. ”

“ Since there is demonstrable evidence that a nerve when no longer in connection with its centre, or with ganglionic cells, may be excited by electricity, pressure, thermal and chemical stimuli, we must conclude that even when it is in connection with its centre, any local irritation from pressure, changes in the circulation, etc., will also excite it. ”

“ When a nerve being cut, paralyzed or irritated in any manner, the organ which receives it undergoes no derangement in its functions, we certainly are unable to appreciate the nervous influence upon this organ. I do not say that it does not exist, but I maintain that we know nothing about it, and that we ought not to employ at hazard a word to which we cannot attach any precise idea. What word will you employ then to express the influence of the nerves upon the organs of the senses, upon the voluntary muscles, &c. ”

“ The afferent nerves are those that convey the impulses from the periphery of the body to the nerve center, which are located in the brain or in the spinal cord. The impulses conveyed are those of special senses, as sight, hearing, taste, touch, and smell. Impulses producing sensation pleasurable or painful come from the skin, the muscle, or the viscera.
The efferent nerves are those which convey impulses from the nerve centers to the periphery. These impulses may be motor as those going to the muscle cells of the skeletal muscles, the viscera, or the blood-vessels. ”

“ The incoming nerve-fibres serve to conduct stimuli or impressions to the cells in the nerve-centre; and, when the cells thus receive a stimulus or impression, they liberate a discharge of nervous energy, which then courses down the outgoing nerve-fibres to be distributed either to other nerve-centres or else to muscles. It is in this way that nerve-centres are able to act in harmony with one another, and so to coördinate the action of the muscles over which they preside. This fundamental principle of neurosis is what physiologists call the principle of reflex action ”

“ The enormous preponderance of cases of pain of the fifth nerve, compared with other nerves, is to be accounted for by the liability of the delicately adjusted mechanism of the organs supplied to get out of order. ”

“ When a stimulus of any kind, whether mechanical, chemical, electrical, or vital, acts upon the living nervous substance, it produces an impression on that nerve substance and excites within it some particular change, and the property by which this takes place in the nerve substance has been called its excitability or neurility. ”

“ I have letters and verbal proofs in quantity proving the efficiency of those rules and suggestions.
So wonderful have been the results, so numerous the recoveries, that the testimonials, if published, would make the fake nerve tonic manufacturer die of envy.
"Only your nerves." I cannot understand why the word, only, is used. It makes it appear that nerves are of minor importance.
Nerves are less understood than anything in the human anatomy.
Experience has proved that nerves cannot be restored by dope, patent medicines, tonics or prescriptions. ”

“ It shows how congestive conditions--or inversely anemic conditions--constitute organic states sufficient to set in movement the activity of the nerve-centers, as is the case for muscular contractility.... Everything leads us to believe that at the moment when the motor nervous action takes place the corresponding sensitive centers also come into play. ”

“ This excitation of the nerve can, however, be induced by very different kinds of processes, namely, by all processes which possess in common the condition that they suddenly increase certain disintegration processes in the living nerve substance. ”

“ It seems, therefore, the inevitable conclusion that a dynamic perturbation going on in the non-nervous tissue is continued along the nerves themselves: and that the severity of the pain perceived by the conscious centres is proportionate to the tumultuousness, the want of coordination, and the waste with which force is being evolved in the cramped muscle, or whatever structure it may be, in which the pain takes its source. ”

“ That which can be done in the way of producing severe pain by these severe affections of the peripheral portions of nerves, or of tissues lying outside them, we might a priori expect would be effected by slighter but continuous changes in the nutrition of the more important portion of the nerve itself—its central gray nucleus. ”

“ In experiments, the animal sensibility of the nerve seems to be gradually exhausted, and finally ceases. I convinced myself of this upon the eighth pair of nerves, in making my experiments upon the injection of black blood into the brain. At the moment the nerve is raised and drawn to detach it from the carotid with which it is connected, the animal cries out and is much agitated; but after the same thing is repeated two or three times, he208 no longer gives any signs of pain. If we cease to excite the nerve for an hour or two, the sensibility returns with great energy, when it is drawn again. ”