THE NERVOUS SYSTEM
WITHOUT some knowledge of the nervous system, it is impossible to understand fully how the mind may affect the body.
To begin with, as every schoolboy knows, each human being has a complex system of nerves, the fountainhead of which is the brain. From the lower part of the brain, in the back of the head, issues the spinal cord, a bundle of nerve-fibers; and from this, nerves branch out and run to all parts of the body, much as branches radiate from the trunk of a tree.
But every one does not know, or else has forgotten, that we have three kinds of nerves--those that move the muscles, called motor nerves, those which receive and
p. 32
carry outside impressions to the brain and called sensory nerves, and those that keep up the bodily activity, keep the fires burning--and these are called sympathetic.
Nervous centers are distributed throughout the body, some along the spinal column, others in the medulla oblongata. At certain places nerves unite forming a plexus,--the cardiac, solar, and hypo-gastric plexuses. The solar plexus is situated just back of the stomach and the hypogastric plexus in the abdomen (Fig. 3).
"The real center of this system," says Dr. Carpenter, the English brain-physiologist, "appears to lie in the medulla oblongata [the bulb at the apex of the spinal cord], and has for its function the regulation of the blood-supply to the different parts by its action on the caliber of the arteries." That is, the great blood-channels, called arteries, which carry the red blood away from the lungs, are surrounded by a branch of these sympathetic nerves (called vasomotor),
FIG. 3.--THE NERVOUS SYSTEM. FIG. 3.--THE NERVOUS SYSTEM.
1. Cerebrum.
4. Cardiac Plexus.
2. Cerebellum.
5. Solar Plexus.
3. Medulla Oblongata.
6. Hypogastric Plexus.
7. Spinal Nerves.
p. 33
which when they contract diminish the size of the channels and hence decrease the amount of blood in them. If you should bandage your arm tightly, you would get the same result; but in the case of the nerves of which we are speaking, the action is automatic and controlled from the center at the base of the brain.
Probably the reason why these nerves were first called "sympathetic" is that if one nerve-center is shocked or does not properly conduct itself, the others sympathize, or reflex the state of the first, and then all sorts of troubles arise.
We have an an*logous experience when heavy storms ravage the country. If you "call up central" on the telephone, desiring to communicate with some distant town, even tho you may "get central," you fail to reach your friend or business a**ociate because of crossed wires, broken poles, etc.
The nervous system, like the telephone
p. 34
company, has its central stations from which lines radiate, and any little side line can get into touch with "central" if the intervening or allied centrals are in good running order.
So then, if there is anything wrong with the central at the base of the brain, the other centrals in the stomach or heart, for example, may become more or less unsettled and behave in a hysterical manner.
But we have said that the automatic activity of these nerves is directed from the center at the base of the brain, hence we may well ask, what directs its action?
Now we are getting down to bed-rock.
The axiom of science that "no force is ever lost" was noted in chapter first, and here we have an illustration of it. The force, chemical and mental, which is generated by the brain through its reaction upon the mind must go somewhere. So this force follows the nerve-fibers leading from the top of the brain down to this center
p. 35
of which we are speaking and quickens it into action. The center automatically reacts upon the force and sends it flashing with incredible speed down the spinal cord; and thence it follows the branching nerves in every direction to the uttermost limits of the body; what is unused by the body radiates into space (Fig. 3).
Dr. Benjamin Richardson, an English physician of the past century, claimed to have traced this radiating energy to a distance of eighteen inches from the skin; how much farther it extends we do not know.
Now, it is this vital energy spreading out over the body by means of the nerves which keeps the fires of life burning. It keeps the heart beating, the blood circulating, the stomach digesting; in fact, all the physical processes are dependent upon it. It is therefore the life-stimulus or force. And this can be easily seen. For if it ceases to flow into the arm, for instance,
p. 36
one not only can not move that member, but in course of time it withers. We call it paralysis.
Now if this be true, health must depend primarily upon the quality, quantity, and distribution of this vital energy; for if it depreciate in any respect, all the physical processes are weakened. And if there be a weak spot, there it will be felt to the greatest extent. And there generally is a weak spot. Few, if any of us, are built like the "Wonderful One-Hoss Shay"!
But there is still another phase of the matter.
We have seen that the nerve-center in the medulla regulates the supply of blood in the blood-channels and also in the blood-vessels of every organ or part. And this it does automatically according to the needs of the various parts. Thus, in good health, the thought or smell of food and the act of eating quicken the nerves of the stomach and cause the blood-vessels to expand and
p. 37
fill with blood. And then the digestive secretions pour into the stomach, ready to digest the food. On the other hand, the thought of danger so shocks the automatic center of the brain that the heart, with which it is connected by large nerves, may be temporarily paralyzed.
Hence it must be clear that all the functions of the body are dependent upon the activity of these nerves, which increase or cut off the blood-supply according as the brain is affected. If there is nervous exhaustion, the circulation is weak; consequently there ensue "functional disorders."
Also it follows that if the supply of blood to any organ or part is depleted, the nutrition of that part will be impaired. For the blood-stream contains the elements of nutrition by means of which the tissues are constantly built up. The daily tissue-waste can be repaired only through the blood, and hence the ultimate integrity
p. 38
of all parts depends upon the supply of blood, and also the quality of the blood. For if the blood contains impurities, the parts can not be renewed any more than you can repair a garment with rotten cloth or build a house of decayed wood.
To sum up: From this sympathetic nerve-center at the base of the brain, the mental or life-energy liberated by the brain pa**es by way of the spinal cord and nerves to all parts of the body, giving life or quickening into action each and every part. It controls the supply of blood to all parts, varying it at need. Without it all physical processes would cease; and upon its presence depends the circulation of each part and consequently the healthy condition of each part.
And thus become apparent two fundamental essentials of health: the quality, quantity, and distribution of the vital energy and the blood.
It is now plain what becomes of the force
p. 39
generated by ideas in a state of action. First, they play upon the brain, as the wind plays upon the water; this sets up waves or currents in the brain-stuff; the molecules are displaced or rearranged, and this sets free a new kind of force, which must be mental, since the mind begot it.
This mental energy then flows down from the brain; like the sap rising in the tree and penetrating to the outermost twigs, it flows by way of the nervous system to the extreme limits of the body. And it is the life-force, since, if it is impaired, all the vital processes are weakened.