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White matter is the tissue through which messages pass between different areas of grey matter within the central nervous system. The white matter is white because of the fatty substance (myelin) that surrounds the nerve fibers (axons). This myelin is found in almost all long nerve fibers, and acts as an electrical insulation.
Grey matter, or brain matter in American English, 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. Grey matter is distinguished from white matter in that it contains numerous cell ...
Embedded within the white matter—which is sometimes called the arbor vitae (tree of life) because of its branched, tree-like appearance in cross-section—are four deep cerebellar nuclei, composed of gray matter. [13] Connecting the cerebellum to different parts of the nervous system are three paired cerebellar peduncles.
The anterior and posterior grey columns present as projections of grey matter and are also known as the horns of the spinal cord. The white matter is located outside of the grey matter and consists almost totally of myelinated motor and sensory axons. Columns of white matter known as funiculi carry information either up or down the spinal cord.
Gray ramus communicans; White ramus communicans; The grey and white rami communicantes are responsible for conveying autonomic signals, specifically for the sympathetic nervous system. Their difference in coloration is caused by differences in myelination of the nerve fibres contained within, i.e. there are more myelinated than unmyelinated ...
The white ramus communicans ( pl.: rami communicantes) from Latin ramus (branch) and communicans (communicating) is the preganglionic sympathetic outflow nerve tract from the spinal cord. Each of the thoracic, and the first and second lumbar nerves contribute a white ramus communicans to the adjoining sympathetic ganglion, unlike the gray rami ...
Nervous tissue is made up of different types of neurons, all of which have an axon. An axon is the long stem-like part of the cell that sends action potentials to the next cell. Bundles of axons make up the nerves in the PNS and tracts in the CNS. Functions of the nervous system are sensory input, integration, control of muscles and glands ...
The neocortex consists of the grey matter, or neuronal cell bodies and unmyelinated fibers, surrounding the deeper white matter ( myelinated axons) in the cerebrum. This is a very thin layer though, about 2–4 mm thick. [ 6] There are two types of cortex in the neocortex, the proisocortex and the true isocortex.