Grey matter is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and unmyelinated axons), glial cells (astrocytes and oligodendrocytes), synapses, and capillaries. It is present in the brain, brainstem, cerebellum, and spinal cord. Grey matter contains most of the brains neuronal cell bodies and is distinguished from white matter in that it contains numerous cell bodies and relatively few myelinated axons, while white matter contains relatively few cell bodies and is composed chiefly of long-range myelinated axons. Approximately 40% of the brain consists of grey matter and 60% is made of white matter.
Grey matter consists of neuronal cell bodies (known as soma), which are circular structures that house the nucleus of the cells. The dendrites are short protrusions that communicate with neurons close by. Grey matter plays a significant role in allowing humans to function normally as it allows us to control our movements, retain memories, and regulate our emotions, among many other functions. The structures within the grey matter process signals from the sensory organs or from other areas of the brain. Grey matter is located on the surface of the brain, forming the ridges and grooves (gyri and sulci) . It is also present in parts inside the brain and spinal cord. The highest concentrations of grey matter are in the cerebrum, cerebellum, and brain stem. In the spinal cord, grey matter is located in the center and is shaped like a butterfly if sliced horizontally.
