MJENS SANA IN CORFOUX! SANO. VOL. 16. BATTLE GREEK, MIOH., MAY, 1881. KO. 5. ANATOMY OF THE BRAIN AND NERVES. oughly established facts, devoting little space to the consideration of complicated BY THE K OITOR. and disputed questions connected with the The structure of' the nervous system is subject. the most complex and delicate of any part S t r u c t u r e o f N e r v e T i s s u e .— There are of the body. Many portions of it, indeed, two distinct elements in nerve tissue, cells and fibers. The essential element of both Fig. -2.—A View of the upper surface of the Brain, exposed by turning back the Scalp and removing a por­ tion of the Cranium. of these we find to be the same, the central part of the fiber being but a continuation of the cells, both being composed o f the great basis of all forms o f living matter, protoplasm. F i g . 1 .—A General View o f the Nervous System. These two elements of the nervous sys­ are not yet perfectly well known, although tem are differently distributed in the body. many physiologists have devoted their The cells are collected in groups in the whole lives to careful study of this part of central parts of the body, which are termed the human organism. We shall not at­ ganglia, while the nerve fibers, associated tempt to give any except the most thor­ in bundles, ramify to every part of the 130 GOOD HEALTH. body. So completely is the whole body S t r u c t u r e o f t h e D r a i n .— The brain is permeated by these delicate filaments oc­ the largest mass of nervous matter in the cupied in transmitting sensations and voli­ body, filling the entire cranial cavity. Its tions, that if all the other tissues were re­ weight is about forty-nine and one-half moved, the nerves would still present an ounces in males, and forty-four ounces in exact outline of the body. Divisions of the N er­ vous System.— Consid­ ered from the stand­ point of function, the nervous system is di­ vided into two classes, each of which has a distinct work to per­ form, viz., the cerebro­ spinal system, and the organic or sympathetic system. The first men­ tioned is that with which we have most to deal, because this is the one which chiefly dis­ tinguishes man and ani­ mals from vegetables, F ig. 4.—A View of the under surface of the Brain, and the higher func­ showing the Origins of the Several Pairs of Nerves. tions of which distin­ guish man from lower females. It is inclosed by two membranes, orders of animals. The the outer of which is closely applied to the second class, or system inner plate of the skull, and from its tough­ of nerves, presides over ness called the dura mater. This mem­ the nutritive functions brane abounds in blood-vessels, from which of the body, the pro­ nourishment is supplied to both the brain cesses o f growth and and the skull, and by means of which the repair, excretion, secre­ tion, etc., which are sometimes termed the vegetative functions, be­ cause of their close an- F lo Spina1ic o nr<T' 1 alogy to similar func­ tions in vegetables, al­ ► though in the latter class of existences there is nothing analogous to a nervous system. D e s c r i p t i o n o f t h e C e r e b r o -S p i n a l S y s ­ t e m .— The cerebro-spinal system is made up of ganglia and nerve trunks. The gan­ glia, or groups of cells, are chiefly to be found in the skull and spinal canal, con­ F i g . 5 .— The left half of the Brain, showing the Con­ volutions of the Cerebrum, one Lateral Ventricle, the stituting the brain and spinal cord, the Arbor Vitœ of the Cerebellum, etc. central axis of this system, the nerve trunks emanating from these two great centers blood supply of the interior and exterior of and extending to all parts of the body. the cranium is in communication. Next GOOD HEALTH. 131 the brain is another delicate membrane, the cerebellum, or little brain. Each of chiefly made up of' blood-vessels which run these principal portions of the brain is sub­ down into the substance of the brain. Be- divided by a fold of the membraneous cov­ erings into two lateral halves, each of which furnishes nerves to the opposite half of the body. When the membranes of the brain are removed, its surface is found to be marked by numerous and quite deep depressions, which are due to the convolutions or fold­ ings of its outer layers. The gray color of the mass is also noticeable. When cut, it is found that the gray substance extends but a little way into the mass of tissue, the central portion being white. Examination with a microscope shows that the gray substance is composed of nerve cells, while the white portion is made up o f fibers, which are connected with the cells. A t the base of the brain, or its under side and central portion, are found a number F i g . 6.—A Horizontal Section of the Brain through its of collections o f gray matter or nerve cells, middle portion, showing the relation of the White Mat­ ter to the Gray, with many other points of interest. called the central ganglia of the brain. At the lowest portion of the brain, just tween this membrane and the dura mater at its junction with the spinal cord at the is still another membrane so delicate in its foramen magnum, is a rounded body, structure that it has received a name which known as the medulla oblongata, which describes it as being like a spider’s web. may really be considered as the enlarged The membranes of the brain divide it upper end of the spinal cord. into a larger and a smaller portion. The In the central portion of the brain is larger portion, located in the upper and found a curious little organ about as large as a pea, the piiteal gland, which the great philosopher Descartes supposed to be the seat of the soul. It is now known to be simply a gland. From this exceedingly brief description it will be seen that the brain is really a collection of ganglia within the skull, and consists of several distinct groups of cells. Each group has its particular function to perform, its particular part o f the work of the vital economy to control or direct. Prom each one go out nerve fibres which terminate in different ways, according to the functions to be performed. —Evil thoughts are worse enemies than F i g . 7.—A view of the Cranial Nerves, with their lions or tigers; for we can keep out of the points of origin in the Brain. way of wild beasts, but bad thoughts win their way everywhere. The cup that is front part o f the skull, is called the cere­ full will hold no more. Keep your head brum ; the smaller portion, located in the and heart full of good thoughts, that bad back and lower part of the skull, is called ones may find no room to enter. 132 GOOD HEALTH. THE TOBACCO CURSE. its various forms as truly slaves as were our Southern negroes ! Is not its bondage U n d e r the head of “ The Tobacco Prob­ as oppressive as was theirs ? Are not its lem,” a pointed writer, Meta Lander, deals fetters as tightly riveted ? out most vigorous strokes against this gi­ This tobacco vice—for I can call it gantic evil. Of the use of tobacco, we nothing less— extends to every nation on may forcibly say in the words of Sacred the globe and pervades every rank in so­ W rit, “ It is evil, and only evil, and that ciety. The gray-haired patriarch is not continually .” As Shakespeare wrote of too old, nor the hoy of twelve too young wine, “ If thou hast no other name to go to be its willing subject. Neither the by, let’s call thee devil! ” so may we say filthiest slum nor the politest society is of tobacco. Perhaps the well-known free from it. couplet is not far amiss, It stalks defiantly through the streets, “ Tobacco is a poisonous weed, fouling the very air of heaven. It boldly It was the devil sowed the seed.” sits in our legislative halls, both state and At any rate, if the evil one did not sow national. It enters the temple o f the the seed, as the noted Dr. Clarke seems to Lord, and even creeps up to the altar. more than half believe, he certainly has It travels shamelessly on water and on something to do in raising it, and in lead­ land. In spite of special arrangements to ing about seven-tenths of the civilized imprison it, there is no such thing as world to use it. O thou insidious demon, shutting it away from the tell-tale air and T o b a c c o ! enemy of finance, destroyer of the whispering breeze. health, and the gross perverter of morals ! The office of the lawyer and of the phy­ Well may the pure, the clean, the virtuous, sician and the sanctum of the minister o f every land, pronounce against thee, are alike under its offensive cloud.