By analolgy, the grey matter is like the CPU in a computer and
the white matter is like the printed circuit board that connects
it to the other parts of the computer. The white matter is so-
called because it contains lots of nerve fibres (neurons) that
are sheathed in a white fatty insulating protein called myelin.
In section, myelin is white whereas the grey matter is grey due
to all the grey nuclei in the cells that make it up. Multiple
Sclerosis is predominantly a disease of the white matter in the
central nervous system. About 95% of all lesions associated with
multiple sclerosis occur in the white matter. The white matter
is found in the inner layer of the cortex, the optic nerves, the
central and lower areas of the brain (notably the Brainstem) and
surrounding the central shaft of grey matter in the spinal cord.
White Matter Links: