White matter

White matter is a component of the central nervous system (CNS) that transmits signals between different parts of the CNS. It is composed of myelinated axons, which are nerve fibers coated with a fatty substance called myelin. This myelin sheath helps to speed up the transmission of nerve signals.

White matter is found in the deeper tissues of the brain (subcortical), as well as the outer layer of the spinal cord. It is named for its relatively light appearance when fresh, due to the lipid content of myelin.

Structure

White matter is composed of bundles of myelinated nerve cell projections (or axons), which connect various gray matter areas (the locations of nerve cell bodies) of the brain to each other, and carry nerve impulses between neurons. The axons are wrapped in a type of fat called myelin, which gives the white matter its color.

Function

The main function of the white matter is to transmit signals from one region of the cerebrum to another and between the cerebrum and lower brain centers. White matter in the brain helps regulate various brain functions.

Clinical significance

Damage to areas of white matter can interfere with the speed and efficiency of nerve signal transmission, and can lead to a variety of neurological disorders, such as multiple sclerosis and Alzheimer's disease.

See also

• Gray matter
• Myelin
• Central nervous system

References

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