The Brain

Enclosed within the skull is the central organ of the nervous system--the brain. There are "three major divisions of the brain: the forebrain, the midbrain, and the hindbrain."

[pg. 324, WEBSTER'S NEW INTERNATIONAL UNABRIDGED DICTIONARY (c) 1954, 2nd Edition]

The appearance of the brain is made up of both grey and white matter that can be "divided into several parts". At first glance, the surface of brain is made up of grey matter and forms what is "convolutions of the cerebrum, and the laminae of the cerebellum"...."grey matter is found in the interior of the brain, collected into large and distinct masses or ganglionic bodies, such as the corpus striatum, optic thalamus, and corpora quadrigemina." Under this first layer, the "...grey matter is found intermingled intimately with the white, but without definite arrangement..." And in the third layer "the white matter of the brain is divisible into three distinct classes of fibres: diverging, comissural, and associations fibres."

[pg. 47,  GRAY'S ANATOMY by Henry Gray F.R.S (c) 1995, 15th Edition]

Grey Matter

The grey matter of the brain is "made up largely of nerve cells".

[pg. 324, WEBSTER'S NEW INTERNATIONAL UNABRIDGED DICTIONARY (c) 1954, 2nd Edition]

White Matter

The white matter of the brain is "made up chiefly of nerve fibres arising from the nerve cells of the brain".

[pg. 324, WEBSTER'S NEW INTERNATIONAL UNABRIDGED DICTIONARY (c) 1954, 2nd Edition]