Nervous system. Cerebrospinal nervous centre. — Cerebrum. — Cerebellum.—Isthmus of the encephalon.—Medulla oblongata.—Spinal cord. —Membranes; dura mater, arachnoid, pia mater.—Nerves; cranial nerves, spinal nerves, great sympathetic.—Functions of the nervous system; functions of the spinal nerves of motion and of sensation; function of the cranial nerves; Junctions of the spinal marrow.—Functions of the encephalon; medulla oblongata, pons Varolii, peduncles of the cerebrum and cerebellum, corpora quadrigemina, pineal gland, optic thalami, cerebrum and cerebellum.—Functions of the great sympathetic. —Reflex power.—Nerve force.—Memory.

The nervous system comprises the cerebrum and cerebellum, the spinal cord, and the nerves. It is divided into two portions, the one central, and the other external or peripheric. The first has received the name of the cerebrospinal nervous centre, because it is constituted by the organs which form the encephalon and by the spinal cord. The second is the whole of the nerves proper. Starting from the nervous centre, of which they are the expansion, they are distributed to the whole body. They transmit motive or functional impulses from the nervous centre to every part of the organism; and the impressions of sensibility from the periphery, that is to say from the different points of the body to the nervous centre.

The cerebrospinal nervous centre appears in the form of a soft pulpy symmetrical trunk. Its upper portion is an oval enlargement contained within the cranium, and is called ths encephalon or brain. The lower portion is elongated on leaving the cranium in the form of a spindle—it is the spinal marrow, and is contained in the vertebral canal.