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17. By this cut you can see the manner in which the nerves pass
from the brain and spinal marrow. There
17. Describe the cut. How many pairs of nerves proceed from the brain ?
The First Pair, called the olfactory nerves, proceed from the lower part of the brain, and are spread over the membranes of the nose, to enable us to smell.
The SECOND PAIR, called the optic nerves, or the nerves of sight, lead to the interior of the eye.
The THIRD, FOURTH, and sixth PAIR also proceed to the eye, but are merely connected with the muscles of the
eye, and do not assist our sight at all. 18. The FIFTH PAIR, which has three branches, send one to the eye, others to the nose, the jaw, and the tongue. The nerves sent to the tongue are the nerves of taste.
The SEVENTH PAIR is called the facial nerve, and is sent to the muscle of the face. The EIGHTH
PAIR extends to the ears, called the auditory nerve, by which we hear.
The NINTH, TENTH, ELEVENTH, and TWELFTH pass to the lungs, stomach, tongue, and to the muscles of the neck.
These different pairs of nerves are represented in the cut by figures.
19. There is one very important nerve called the great sympathetic, formed by little cords which rise from several of the other nerves. It extends along down by the spine, enters the chest and stomach, and
17. What is the first pair called ? Where do they proceed, and what is their purpose? What is the second pair called ? Where do they proceed, and what is their purpose ? Where do the third, fourth, and sixth pair lead? What is their use ? 18. Where do the branches of the fifth pair lead? What are the nerves which are sent to the tongue? What is the seventh pair called? Where does it lead? What is the eighth pair called? What is its function? Where do the ninth, tenth, eleventh, and twelfth pair proceed? How are these different nerves represented
19. What is the name of one of the most important nerves ! Of what is this composed ? Where is it situated ?
in the cut?
NERVES OF THE BRAIN.
sends branches to all the important organs. This seems to be a connecting link between all the other parts of the body; so that when one part suffers, the others sympathize or suffer with it.
20. There are thirty nerves, called the spinal nerves that pass off on each side from the spinal marrow. These are distributed to all the muscles of the body. They extend in every direction ; and if all the remain der of the body should be destroyed, except the nerves, they would still present the appearance of a living body, as you can see by looking at the cut on page 19, which represents the nervous system only, or our bodies just
19. Why is this nerve important ? 20. How may nerves pass from the spine? What are they called? Where do they extend ? How would the nerves appear if the rest of the body were destroyed ?
as they would appear if the skin, bones, and muscles, were removed.
21. So minute, extensive, and sensitive, are the nerves, that if we even pricki our fingers, the sensation is immediately conveyed to the brain. It is not the vein which gives us pain, for this is destitute of feeling; it is not the blood, for this is also insensible ; but it is the little, delicate, sensitive nerve that communicates the feeling to the brain as quick as thought.
22. The brain and spinal marrow are like two large rivers, and all the little veins are like so many little streams. It is well, therefore, that there is a connexion between the brain and the different parts of the body, and that the nerves do produce feeling and sensation. We might hold our hand in the fire till it was consumed, if there were no nerves to tell us when the fire was too hot: we might take food into our stomachs so hot that they would soon be destroyed, if we had no nerves in our mouths and throats to enable us to moderate the temperature of our food.
23. Though these nerves frequently cause us much pain and trouble, yet if they did not serve as restraints to us, we might injure our bodies every day, until they would be unable to sustain us. Let us, therefore, take care of them ; for if they be injured, the parts or limbs where they are situated become useless or motionless.
21. What takes place when we prick our fingers ? Why is this effect produced? Why does not the vein give us pain? Why does not tho blood give us pain? What is it that communicates sensation to the brain? 22. What are the brain and spinal marrow? What are the little nerves ? What wise relation is there between the nerves and the brain? What would be the results if we had no nerves? 23. Of what are the nerves the cause? What service are they to us? Why should we take care of them?
24. It is the nervous system which gives animals a higher rank than vegetables. The lowest animal has some nerves; and the more elevated the animal the more extensive and perfect is his nervous system, up to man, in whom it is found in perfection. Man is, therefore, universally acknowledged to be far superior, naturally, to the brutes, although he does not always use his powers to the best advantage.
25. It is and has been generally admitted, that the brain is the seat of the mind ; but this general idea was not sufficient to satisfy every one. Dr. Gall, who lived in Germany nearly a hundred years since, was one of those who were not satisfied with this explanation. He was a very inquisitive lad when young, always looked around him, and thought about what he saw.
26. He noticed among his schoolmates that some of them were very generous and amiable, some selfish, some obstinate and cruel, others kind and affectionate. He found that one liked the study of arithmetic, another could commit to memory, and so on. When reflecting on these things the thought occurred to him that there is always harmony in the works of nature, and that there is a cause which produces every effect. He became convinced that there must be a cause why he could not recite his lessons as rapidly and as freely as some of the other boys. He was very observing, and
24. What is the great difference between animals and vegetables > Has every animal nerves? Who has a perfect nervous system? Whero does it place man in the scale of living beings ? 25. What is the brain generally admitted to be? Did this general idea satisfy every one? Who was Dr. Gall? 26. What did he notice among his schoolmates? What did this lead him to do? What was the result of reflection? Of what did he feel convinced? Did he ascertain the cause of the difference be tween his schoolmates and himself?