Skip to main content
Select Source:

grey matter

grey matter comprises those regions in the brain and spinal cord that consist predominantly of the ‘cell bodies’ of nerve cells (neurons).

The nervous system is composed of many types of body tissue, but the most important is nervous tissue itself. The component cells are nerve cells or neurons. Just like cells elsewhere in the body, each neuron has a cell body, with a nucleus (containing the chromosomes with the genetic programs) and cytoplasm for metabolism and the production of proteins. But neurons also have several rather special features, in particular two types of processes extending out from the cell body. Typically, there is a nerve fibre or axon, which can be a metre or more in length, along which impulses travel to convey information to other neurons, or to muscles or glands. In addition, there are several dendrites (from the Greek for ‘wood’ or ‘tree’), up to 2 mm long, on which the axons of other neurons terminate, forming synapses.

In the central nervous system (CNS) — made up of the brain and spinal cord — nerve cell bodies are usually found closely packed together in characteristic regions. Such a concentration of cell bodies, together with their dendrites, but with a relatively small proportion of axons, appears grey in a fresh cut through the brain or cord and is called ‘grey matter’. It forms a relatively thin surface layer, called ‘cortex’ over the cerebral hemispheres and the cerebellum. The spinal cord has a central core of grey matter, which has the shape of a butterfly when cut across. Elsewhere, there are clumps of grey matter called ‘nuclei’, making up such structures as the hypothalamus, the thalamus, and the basal ganglia.

Where mainly axons are concentrated, in most of the rest of the brain and around the outside of the grey matter of the spinal cord, the predominant colour when cut is whitish, because many of the axons are surrounded by a pale, fatty sheath, consisting of myelin. This forms the white matter.

The brain, and particularly the cerebral cortex, has for long been associated with ‘intellect’. The use of the expression ‘grey matter’ has, therefore, appeared in common parlance to mean intelligence, but there is little evidence to suggest that this quality is directly connected to the size of an individual brain.

Laurence Garey


See nervous system.See also central nervous system; nerves.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"grey matter." The Oxford Companion to the Body. . Encyclopedia.com. 23 Feb. 2018 <http://www.encyclopedia.com>.

"grey matter." The Oxford Companion to the Body. . Encyclopedia.com. (February 23, 2018). http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/grey-matter

"grey matter." The Oxford Companion to the Body. . Retrieved February 23, 2018 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/grey-matter

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

grey matter

grey matter Part of the tissue that makes up the central nervous system of vertebrates. It is brown-grey in colour, consisting largely of nerve cell bodies, synapses, and dendrites. The grey matter is the site of coordination between nerves of the central nervous system. Compare white matter.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"grey matter." A Dictionary of Biology. . Encyclopedia.com. 23 Feb. 2018 <http://www.encyclopedia.com>.

"grey matter." A Dictionary of Biology. . Encyclopedia.com. (February 23, 2018). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/grey-matter-0

"grey matter." A Dictionary of Biology. . Retrieved February 23, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/grey-matter-0

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

grey matter

grey matter Tissue of the central nervous system which contains a high density of nerve cell bodies. Grey matter occurs in the cortex of the cerebrum and that of the cerebellum, and forms an H in a cross-section of the spinal cord. Compare WHITE MATTER.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"grey matter." A Dictionary of Zoology. . Encyclopedia.com. 23 Feb. 2018 <http://www.encyclopedia.com>.

"grey matter." A Dictionary of Zoology. . Encyclopedia.com. (February 23, 2018). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/grey-matter

"grey matter." A Dictionary of Zoology. . Retrieved February 23, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/grey-matter

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

grey matter

grey matter (gray) n. the darker coloured tissues of the central nervous system, composed mainly of the cell bodies of neurones, branching dendrites, and glial cells. Compare white matter.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"grey matter." A Dictionary of Nursing. . Encyclopedia.com. 23 Feb. 2018 <http://www.encyclopedia.com>.

"grey matter." A Dictionary of Nursing. . Encyclopedia.com. (February 23, 2018). http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/grey-matter

"grey matter." A Dictionary of Nursing. . Retrieved February 23, 2018 from Encyclopedia.com: http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/grey-matter

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.