Object Lessons on the Human Body Part 17

The brain must be used;

The brain must be rested;

I must drink wholesome drink, eat wholesome food, take enough exercise, and breathe pure air, that my brain may be supplied with pure blood;

I must study and think, that my brain may grow and be strong for work;

I must rest my brain when it is tired, either by changing my employment, or by going to sleep;

I must not poison my brain with alcohol or tobacco.

[3] NOTE.--_A fuller description of the Nerves of the Brain_: Twelve pairs of nerves pa.s.s from the base of the brain; the first pair, called the nerves of smell, to my nose; the second pair, called the nerves of sight, to my eyes; the third, fourth, and sixth pairs to the muscles of my eyes; the fifth pair to my forehead, eyes, nose, ears, tongue, teeth, and different parts of my face; the seventh pair to different parts of my face; the eighth pair, called the nerves of hearing, to the inner part of my ear; the ninth pair to my mouth, tongue, and throat; the twelfth pair to my tongue; the eleventh pair to my neck; the tenth pair to my neck, throat, lungs, stomach, and different parts of my body.

QUESTIONS ON THE FORMULA.

1. Describe the brain.

2. Where is the brain placed?

3. Describe the outer membrane of the brain.

4. Describe the middle membrane of the brain.

5. Describe the inner membrane of the brain.

6. Tell about the nerves.

7. Tell about the use of the two kinds of nerves.

8. Tell about the nerves which pa.s.s from the brain.

9. Tell about the spinal cord.

10. Tell about the nerves which pa.s.s from the spinal cord.

11. What happens if a nerve be destroyed?

12. What happens if a nerve be pressed upon too long?

13. What happens if you drink alcoholic liquors, or snuff, smoke, or chew tobacco?

14. What is necessary if you would have a healthy brain?

THE BRAIN AND ITS WORK.

The brain is egg-shaped, and of two parts, the large brain (_cerebrum_), and the little brain (_cerebellum_). These are composed of a white and gray substance, which in the large brain is so folded and wrinkled that it looks like the meat of an English walnut; in the little brain it is so arranged that it resembles a tree, and is called _arbor vitae_, tree of life. The mind does its thinking through the large brain, and controls its muscles through the little brain.

A drunken man can not walk straight because alcohol has hurt the little brain; he can not think straight because it has poisoned the large brain.

[Ill.u.s.tration: THE BRAIN AND THE SPINAL CORD.]

C, the large brain (_cerebrum_). B, the small brain (_cerebellum_). S, a portion of the spinal cord.

QUESTIONS ON THE NERVOUS SYSTEM.

Where is your brain?--"In my skull."

What color is the brain?--"Gray and white."

What does the brain resemble?--"Marrow."

How is the brain protected?--"By three coats or membranes."

What may you name these membranes?--"The outer membrane, the middle membrane, and the inner membrane."

Describe the outer membrane. See Formula.

Describe the middle membrane. See Formula.

What are the nerves?--"White ashen-gray pulpy cords, which are found in the brain."

Where do they go from the brain?--"To every part of the body."

How many kinds of nerves have you?--"Two."

What names are given to the two kinds of nerves?--"Nerves of motion and nerves of feeling."

Which is the largest nerve in the body?--"The spinal cord."

Where is the spinal cord?--"It extends from the brain throughout the whole length of the backbone."

How may you describe the spinal cord?--"It is a bundle of nerves, etc." See Formula.

Where are the spinal nerves?--"They pa.s.s from the spinal cord to different parts of the trunk and limbs."

How many pairs of nerves pa.s.s from the base of the brain?--"Twelve."

Where do the first pair go?--"To the nose."

What are they called?--"The nerves of smell."