Mental Diseases and Their Modern Treatment | Page 4

lesser importance are the third, fourth, and fifth. The lateral are large and occupy a considerable part of the cerebral center, running in a general way lengthwise along the base, but always, according to Hogarth's line of beauty, on a curve. The ventricles are important, because we find in them the choroid plexuses which, when diseased tend to produce sleeplessness, and insanity.
The next in importance to the lateral ventricles is the fourth ventricle. This is bounded in front and below by the medulla, and the reverse of the pons which constitute its floor; above and behind by the cerebellum; in front by the valve of Vieussens, and the superior peduncle; on the side by the restiform bodies, part of the pons, and the lateral lobes of the cerebellum. It is said that diabetes is due to some diseased condition found in the floor of the fourth ventricle.
The third ventricle extends anteriorly along the base of the brain to and between the optic thalami.
The space between the septum lucidum, which is very slight, is called the fifth ventricle.
All the true ventricles communicate with one another; the two lateral with the third, the third with the fourth at the aqueduct of Sylvius, the fourth with the central canal of the spinal cord and with the subarachnoid space.
The significance of the ventricles lies in the fact that effusions occur in them and thus the action of the brain is either impaired, or destroyed.
The cerebellum, or little brain, is supposed to preside over the functions of co-ordination, as they relate to equilibrium, harmony and the symmetrical action of the two parts of the body.
The medulla oblongata is the butt end of the spinal cord. The band of union between this end of the cord, the cerebellum, and the cerebrum is termed the pons varolii.
Viewing the brain from the standpoint of development, we find that it is divided into three parts:
1. The forebrain, consisting of the olfactory lobes, the cerebral hemispheres, and the parts surrounding the third ventricle. 2. The midbrain, consisting of the corpora quadrigemini, and the crura cerebri. 3. The hindbrain, consisting of the cerebellum, the pons varolii, and the medulla oblongata.
This is the classification of Huxley, and is simple and easily remembered.
The physiological peculiarity of the brain is that it selfishly requires for its proper nourishment about one-sixth of all the blood in the entire body.
The brain in the newborn infant is said to weigh about ten ounces. The average weight of the adult brain ranges from forty to forty-eight ounces. The brain of the celebrated Cuvier weighed over sixty-four ounces, that of Abercrombie sixty-three, while those of Agassiz, Daniel Webster, and a common day laborer weighed about fifty-three ounces each. The size of any given brain, all other things being equal, determines its power. But the quality must also be considered. This varies greatly. The brain of Gambetta weighed but thirty-six ounces, while the brain of a United States idiot weighed sixty-seven ounces. The difference in the brain power depends not alone upon the size, but also upon the quality. The quality of the brain can generally be determined by its achievements.
Great differences of opinion have existed with regard to the period at which brains attain their full size. Sir William Hamilton asserted that the brain reached its maturity, as to size, at the age of seven years. Other celebrated writers have claimed that the brain matures between the twentieth and thirtieth years. We believe that under ordinary usage the brain matures gradually with the body, and so long as the general system maintains growth, so long the brain may continue to grow. The head of Napoleon was small in youth, but acquired in after life an enormous development. So it seems that the force of an untiring and active brain may assert itself even against its body environments.
We come now to speak of the functions performed by the brain. These may be divided into two classes: (1) Those which preside over and direct the various motions of the body, physical functions, so to speak; (2) the higher or mental functions, wherein are involved cognizance, memory, and judgment.
The action of the brain, in its relation to the body, may be illustrated by comparing it to the action of a spider in relation to its web. This famous animal is usually found at home in the most central portion of its self-constructed domicile. It may be apparently asleep, but if you touch ever so lightly one of the filaments of the spider's web, he instantly takes notice of the fact, and seeks to repair the injuries which have been wrought. So the brain stands like a sleepless Cerberus in the center of the much-diverging nerve fabric, and if you prick a nerve extremity the shock is vibrated with lightning-like rapidity to the