White matter of the brain

White matter is found in the deeper tissues of the brain (subcortical). It contains nerve fibers (axons), which are extensions of nerve cells (neurons). Many of these nerve fibers are surrounded by a type of sheath or covering called myelin. Myelin gives the white matter its color. It also protects the nerve fibers from injury. Also, it improves the speed and transmission of electrical nerve signals along extensions of the nerve cells called axons.

By comparison, gray matter is tissue found on the surface of the brain (cortical). It contains the cell bodies of neurons, which give gray matter its color.


The major areas of the brain have one or more specific functions.

Gray and white matter of the brain

The tissue called gray matter in the brain and spinal cord is also known as substantia grisea, and is made up of cell bodies. White matter, or substantia alba, is composed of nerve fibers.