Which type of brain matter primarily consists of myelinated nerve fibers?

The type of brain matter that primarily consists of myelinated nerve fibers is white matter. Myelin is a fatty substance that surrounds and insulates nerve fibers, facilitating the rapid transmission of electrical signals between neurons. This myelination gives white matter its distinctive color, which contrasts with gray matter, where neuronal cell bodies, dendrites, and unmyelinated axons are predominantly found.

In the brain, white matter is essential for communication between different brain regions and is involved in various functions, including motor control and sensory information processing. The presence of myelinated fibers in white matter enhances the speed and efficiency of neural signaling, which is crucial for coordinated brain activity.

Gray matter does not have a significant amount of myelination, as it mainly comprises neuronal cell bodies. Cerebellar matter refers specifically to the structure of the cerebellum, which contains both gray and white matter. Subcortical matter also includes various types of tissues, but it does not specifically denote the myelinated nature of white matter. Thus, the presence of myelinated fibers is what distinctly characterizes white matter in the brain.