Grey matter

gray mattergraygreythe little grey cellsbrain mattergray matter tissuegray substancegrey mattegrey matter structure of the human brainlaminae IX
Grey matter (or gray matter) is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and myelinated as well as unmyelinated axons), glial cells (astrocytes and oligodendrocytes), synapses, and capillaries.wikipedia
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Central nervous system

CNScentralcentral nervous system (CNS)
Grey matter (or gray matter) is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and myelinated as well as unmyelinated axons), glial cells (astrocytes and oligodendrocytes), synapses, and capillaries.
The CNS is composed of white and gray matter.

Myelin

myelin sheathmyelinationmyelinated
Grey matter (or gray matter) is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and myelinated as well as unmyelinated axons), glial cells (astrocytes and oligodendrocytes), synapses, and capillaries. 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 The colour difference arises mainly from the whiteness of myelin.
Myelination continues through adolescence and early adulthood and although largely complete at this time, myelin sheaths can be added in grey matter regions such as the cerebral cortex, throughout life.

Brain

brain functionmammalian braincerebral
It is present in the brain, brainstem and cerebellum, and present throughout the spinal cord.
Visually, the interior of the brain consists of areas of so-called grey matter, with a dark color, separated by areas of white matter, with a lighter color.

Axon

axonsnerve fiberaxonal
Grey matter (or gray matter) is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and myelinated as well as unmyelinated axons), glial cells (astrocytes and oligodendrocytes), synapses, and capillaries.
The myelin gives the white appearance to the tissue in contrast to the grey matter of the cerebral cortex which contains the neuronal cell bodies.

White matter

whitewhite brain matterwhite matter tracts
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 The colour difference arises mainly from the whiteness of myelin.
The other main component of the brain is grey matter (actually pinkish tan due to blood capillaries), which is composed of neurons.

Cerebral hemisphere

hemispherecerebral hemisphereshemispheres
Grey matter is distributed at the surface of the cerebral hemispheres (cerebral cortex) and of the cerebellum (cerebellar cortex), as well as in the depths of the cerebrum (thalamus; hypothalamus; subthalamus, basal ganglia – putamen, globus pallidus, nucleus accumbens; septal nuclei), cerebellar (deep cerebellar nuclei – dentate nucleus, globose nucleus, emboliform nucleus, fastigial nucleus), brainstem (substantia nigra, red nucleus, olivary nuclei, cranial nerve nuclei).
Each of these hemispheres has an outer layer of grey matter, the cerebral cortex, that is supported by an inner layer of white matter.

Thalamus

thalamicMetathalamusthalami
Grey matter is distributed at the surface of the cerebral hemispheres (cerebral cortex) and of the cerebellum (cerebellar cortex), as well as in the depths of the cerebrum (thalamus; hypothalamus; subthalamus, basal ganglia – putamen, globus pallidus, nucleus accumbens; septal nuclei), cerebellar (deep cerebellar nuclei – dentate nucleus, globose nucleus, emboliform nucleus, fastigial nucleus), brainstem (substantia nigra, red nucleus, olivary nuclei, cranial nerve nuclei).
The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter in the dorsal part of the diencephalon of the brain with several functions such as relaying of sensory signals, including motor signals to the cerebral cortex, and the regulation of consciousness, sleep, and alertness.

Cerebellum

cerebellarcerebellar cortexcerebellar nuclei
It is present in the brain, brainstem and cerebellum, and present throughout the spinal cord. Grey matter is distributed at the surface of the cerebral hemispheres (cerebral cortex) and of the cerebellum (cerebellar cortex), as well as in the depths of the cerebrum (thalamus; hypothalamus; subthalamus, basal ganglia – putamen, globus pallidus, nucleus accumbens; septal nuclei), cerebellar (deep cerebellar nuclei – dentate nucleus, globose nucleus, emboliform nucleus, fastigial nucleus), brainstem (substantia nigra, red nucleus, olivary nuclei, cranial nerve nuclei). However, several cross-sectional studies have shown that repeated long-term cannabis use is associated with smaller grey matter volumes in the hippocampus, amygdala, medial temporal cortex, and prefrontal cortex, with increased grey matter volume in the cerebellum.
The unusual surface appearance of the cerebellum conceals the fact that most of its volume is made up of a very tightly folded layer of gray matter: the cerebellar cortex.

Brainstem

brain stembrain-stemback of the skull
It is present in the brain, brainstem and cerebellum, and present throughout the spinal cord. Grey matter is distributed at the surface of the cerebral hemispheres (cerebral cortex) and of the cerebellum (cerebellar cortex), as well as in the depths of the cerebrum (thalamus; hypothalamus; subthalamus, basal ganglia – putamen, globus pallidus, nucleus accumbens; septal nuclei), cerebellar (deep cerebellar nuclei – dentate nucleus, globose nucleus, emboliform nucleus, fastigial nucleus), brainstem (substantia nigra, red nucleus, olivary nuclei, cranial nerve nuclei).

Spinal cord

medulla spinalisspinethoracic segment
It is present in the brain, brainstem and cerebellum, and present throughout the spinal cord.
Internal to this peripheral region is the grey matter, which contains the nerve cell bodies arranged in the three grey columns that give the region its butterfly-shape.

Grey column

horns
Grey matter in the spinal cord is known as the grey column which travels down the spinal cord distributed in three grey columns that are presented in an "H" shape.
The grey column refers to a somewhat ridge-shaped mass of grey matter in the spinal cord.

Cranial nerve nucleus

cranial nerve nucleimotor nucleicranial nuclei
Grey matter is distributed at the surface of the cerebral hemispheres (cerebral cortex) and of the cerebellum (cerebellar cortex), as well as in the depths of the cerebrum (thalamus; hypothalamus; subthalamus, basal ganglia – putamen, globus pallidus, nucleus accumbens; septal nuclei), cerebellar (deep cerebellar nuclei – dentate nucleus, globose nucleus, emboliform nucleus, fastigial nucleus), brainstem (substantia nigra, red nucleus, olivary nuclei, cranial nerve nuclei).
A cranial nerve nucleus is a collection of neurons (gray matter) in the brain stem that is associated with one or more cranial nerves.

Subthalamus

prethalamussubthalamic
Grey matter is distributed at the surface of the cerebral hemispheres (cerebral cortex) and of the cerebellum (cerebellar cortex), as well as in the depths of the cerebrum (thalamus; hypothalamus; subthalamus, basal ganglia – putamen, globus pallidus, nucleus accumbens; septal nuclei), cerebellar (deep cerebellar nuclei – dentate nucleus, globose nucleus, emboliform nucleus, fastigial nucleus), brainstem (substantia nigra, red nucleus, olivary nuclei, cranial nerve nuclei).

Anterior grey column

ventral hornanterior hornanterior horn of the spinal cord
The forward-facing column is the anterior grey column, the rear-facing one is the posterior grey column and the interlinking one is the lateral grey column.
The anterior grey column (also called the anterior cornu, anterior horn of spinal cord or ventral horn) is the front column of grey matter in the spinal cord.

Basal ganglia

basal nucleibasalbasal ganglia (BG)
Grey matter is distributed at the surface of the cerebral hemispheres (cerebral cortex) and of the cerebellum (cerebellar cortex), as well as in the depths of the cerebrum (thalamus; hypothalamus; subthalamus, basal ganglia – putamen, globus pallidus, nucleus accumbens; septal nuclei), cerebellar (deep cerebellar nuclei – dentate nucleus, globose nucleus, emboliform nucleus, fastigial nucleus), brainstem (substantia nigra, red nucleus, olivary nuclei, cranial nerve nuclei).
In contrast to the cortical layer that lines the surface of the forebrain, the basal ganglia are a collection of distinct masses of gray matter lying deep in the brain not far from the junction of the thalamus.

Fastigial nucleus

fastigialfastigiinucleus fastigii
Grey matter is distributed at the surface of the cerebral hemispheres (cerebral cortex) and of the cerebellum (cerebellar cortex), as well as in the depths of the cerebrum (thalamus; hypothalamus; subthalamus, basal ganglia – putamen, globus pallidus, nucleus accumbens; septal nuclei), cerebellar (deep cerebellar nuclei – dentate nucleus, globose nucleus, emboliform nucleus, fastigial nucleus), brainstem (substantia nigra, red nucleus, olivary nuclei, cranial nerve nuclei).
It is one of the four deep cerebellar nuclei (the others being the nucleus dentatus, nucleus emboliformis and nucleus globosus), and is grey matter embedded in the white matter of the cerebellum.

Neuropil

neuropil threadsneuropilslobula plate
Grey matter (or gray matter) is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and myelinated as well as unmyelinated axons), glial cells (astrocytes and oligodendrocytes), synapses, and capillaries.

Astrocyte

astrocytesastrogliaastrocytic
Grey matter (or gray matter) is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and myelinated as well as unmyelinated axons), glial cells (astrocytes and oligodendrocytes), synapses, and capillaries.

Rexed laminae

Rexed laminalamina VIIlamina VII and lamina VIII
The grey matter of the spinal cord can be divided into different layers, called Rexed laminae.
The Rexed laminae comprise a system of ten layers of grey matter (I–X), identified in the early 1950s by Bror Rexed to label portions of the grey columns of the spinal cord.

Spinal interneuron

interneuronIa inhibitory interneuron
The grey matter in the spinal cord consists of interneurons, as well as the cell bodies of projection neurons.
Most interneurons are found in the grey column, a region of grey matter in the spinal cord.

Grey commissure

gray commissure
The grey matter on the left and right side is connected by the grey commissure.
The grey commissure is a thin strip of grey matter that surrounds the central canal of the spinal cord and, along with the anterior white commissure, connects the two halves of the cord.

Lateral grey column

lateral columnlateral hornintermediate horn cell
The forward-facing column is the anterior grey column, the rear-facing one is the posterior grey column and the interlinking one is the lateral grey column.
Grey matter in the brain and spinal cord is any accumulation of cell bodies and neuropil (neuropil is tissue rich in nerve cell bodies and dendrites).

Emboliform nucleus

emboliformnucleus emboliformisemboliform nuclei
Grey matter is distributed at the surface of the cerebral hemispheres (cerebral cortex) and of the cerebellum (cerebellar cortex), as well as in the depths of the cerebrum (thalamus; hypothalamus; subthalamus, basal ganglia – putamen, globus pallidus, nucleus accumbens; septal nuclei), cerebellar (deep cerebellar nuclei – dentate nucleus, globose nucleus, emboliform nucleus, fastigial nucleus), brainstem (substantia nigra, red nucleus, olivary nuclei, cranial nerve nuclei).
The emboliform nucleus is a wedge-shaped structure of gray matter found at the medial side of the hilum of the dentate nucleus.

Gray matter heterotopia

periventricular nodular heterotopiaGrey matter heterotopiaheterotopia
* Grey matter heterotopia
Gray matter heterotopias are neurological disorders caused by clumps of gray matter (nodules of neurons) located in the wrong part of the brain.

Hippocampus

hippocampalhippocampihippocampal formation
However, several cross-sectional studies have shown that repeated long-term cannabis use is associated with smaller grey matter volumes in the hippocampus, amygdala, medial temporal cortex, and prefrontal cortex, with increased grey matter volume in the cerebellum.
The hippocampus can be seen as a ridge of gray matter tissue, elevating from the floor of each lateral ventricle in the region of the inferior or temporal horn.