The brain consists of four principal parts: medulla oblongata, pons varilii, cerebrum, and cerebellum. Like the spinal marrow it also has three coverings bearing the same names. The dura mater adheres very firmly to the bones of the cranium and consists of two laminae, which are divided into folds called falx cerebri, tentorium, and falx cerebdi.

The medulla oblongata is the upper part of the spinal cord; it is conical in shape, and extends from the first bone of the spinal column to the pons varolii. Its divisions are the corpori pyramidale, olivare and restiforme.

The pons varolii is cuboidal in shape, and situated just in front of the medulla.

The cerebrum is the largest mass composing the brain. It is oval in shape, and weighs from three to four pounds. It is divided into two hemispheres, each hemisphere consisting of an anterior, middle, and posterior lobe. The surface presents a number of convolutions, or gyri, each separated by deep fissures, or sulci. The interior of each hemisphere is medullary in character, and the surface of each convolution is cineritious for the depth of about one-sixth of an inch.

The ventricles of the brain are five in number: they are called the right and left lateral, the third, fourth, and fifth ventricles.

The more minute anatomy of the cerebrum is exceeding complex, and not of special importance in a popular work of this kind.

The cerebellum constitutes about one-sixth of the brain, and is contained between the occiput and tentorium. It is oblong and flattened in shape, and composed of white and gray substances.


These are nine in number, and all emerge from the foramina, or opening at the base of the brain. They are designated by their function as well as numerically, viz.: 1st, olfactory; 2d optic; 3d, motor oculi; 4th, patheticus; 5th, trifacial; 6th, motor externus; 7th, facial and auditory; 8th, pneumogastric, glosso-pharyngeal, and spinal accessory; 9th, hypoglossal.

According to function the cranial nerves may be divided into three classes, viz.: nerves of special sense, including the lst, 2d, and the auditory branch of the 7th; nerves of motion, including the 3d, 4th, 6th, facial branch of the 7th and 9th; compound nerves, comprising the 8th and 5th.

The principal nerve of the arm is the brachial; of the forearm, the ulnar and radial; of the thigh, the great sciatic, which divides, about one-third above the knee, into two large branches, the peroneal and popliteal; further on the popliteal is called the posterior libial. In the pelvis there are the pudic, gluteal, and lesser ischiatic.

The sympathetic nerve is distributed with all the other nerves of the body, and by means of plexuses supplies all the internal organs.

The nervous system is a complex piece of machinery, and its anatomy requires much study before any competent familiarity with it can be gained. The physician, who has an inadequate knowledge of the anatomy of the nervous system, and philosophy of nervous phenomena, or the physiology pertaining thereto, cannot hope to treat diseases assailing the system with any material success. Competence in this respect is the reward only of a long devotion, and practical experience.