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  2. White matter - Wikipedia

    en.wikipedia.org/wiki/White_matter

    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.

  3. Ramus communicans - Wikipedia

    en.wikipedia.org/wiki/Ramus_communicans

    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 colouration is caused by differences in myelination of the nerve fibres contained within, i.e. there are more myelinated than unmyelinated ...

  4. White ramus communicans - Wikipedia

    en.wikipedia.org/wiki/White_ramus_communicans

    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 ...

  5. Human brain - Wikipedia

    en.wikipedia.org/wiki/Human_brain

    The outer part of the cerebrum is the cerebral cortex, made up of grey matter arranged in layers. It is 2 to 4 millimetres (0.079 to 0.157 in) thick, and deeply folded to give a convoluted appearance. [21] Beneath the cortex is the cerebral white matter. The largest part of the cerebral cortex is the neocortex, which has six neuronal layers.

  6. Grey matter - Wikipedia

    en.wikipedia.org/wiki/Grey_matter

    Grey matter 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. [1] The colour difference arises mainly from the whiteness of myelin. In living tissue, grey matter actually ...

  7. Gray ramus communicans - Wikipedia

    en.wikipedia.org/wiki/Gray_ramus_communicans

    Each spinal nerve receives a branch called a gray ramus communicans (pl.: rami communicantes) from the adjacent paravertebral ganglion of the sympathetic trunk. The gray rami communicantes contain postganglionic nerve fibers of the sympathetic nervous system and are composed of largely unmyelinated neurons.

  8. Spinal cord - Wikipedia

    en.wikipedia.org/wiki/Spinal_cord

    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.

  9. Cerebellum - Wikipedia

    en.wikipedia.org/wiki/Cerebellum

    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. [14] Connecting the cerebellum to different parts of the nervous system are three paired cerebellar peduncles.