What is the function of white mater in the spinal cord?

Answer 1

White and grey matter are essentially made up of bundles of nerve fibers (called neurons) that convey nerve impulses between the peripheral nervous system and the central nervous system. The major difference between white and gray matter within the spinal cord is that white matter is primarily composed of myelinated nerve fibers, while the nerve fibers of gray matter are not. Myelinated nerve cells tremendously increase the speed at which the action potential (nerve impulse) moves along the neurons axon. The job of the neurons that make up white matter is to either convey an action potential from a sensory receptor to the central nervous system, or, from the central nervous system out to an effector (such as a muscle or tissue). These neurons are called sensory neurons and motor neurons respectively. Gray matter consists of unmyelinated neurons, called interneurons. Their main duty is to provide communication between the peripheral and central nervous systems. Think of interneurons as a bridge linking two regions together. For unmyelinated neurons, the speed at which an action potential can propagate down the cell's axon is far less than that of the myelinated neurons of white matter.

Answer 2

In the spinal cord, white matter is the tissue in which messages pass between different areas of gray matter within the nervous system. (It makes the connection between gray matter.)