Gray matter

Gray matter is one of the two types of tissue found in the central nervous system, the other being white matter. It contains a high concentration of neuronal cell bodies and their accompanying axon terminals and dendrites, all surrounded by neuroglia and blood vessels. The grey color comes from the cell bodies and the absence of myelin.

In the brain, gray matter forms the outer cortical layer of the cerebrum and cerebellum (i.e. the cerebral and cerebellar cortices). It is also present in the deeper parts of the cerebrum (such as the thalamus, basal ganglia, and other subcortical nuclei), cerebellum (deep cerebellar nuclei), and brainstem.

In the spinal cord, the gray matter extends down and has a butterfly shape with anterior and posterior horns. The anterior horns control motor movements, while the posterior horns receive sensory signals, allowing interaction between the environment and the body. In certain regions of the spinal cord (from T1 to L2 segments), there is an additional lateral gray horn that regulates the autonomic nervous system by activating the sympathetic nervous system.