gray matter

1. Brownish-gray nerve tissue, especially of the brain and spinal cord, composed of nerve cell bodies and their dendrites and some supportive tissue.
2. Informal. Brains; intellect.

noun

The seat of the faculty of intelligence and reason: brain, head, mind. See thoughts.

Brains, intellect, as in If you'd only use your gray matter, you'd see the answer in a minute. This expression refers to actual brain tissue that is gray in color. Agatha Christie's fictional detective, Hercule Poirot, constantly alludes to using the little gray cells for solving a crime. [Late 1800s]

Gray areas of brain and spinal cord made up primarily of cell bodies and dendrites of nerve cells rather than myelinated axons. White matter or substance is the tissue composed primarily of myelinated, or medullated, fibers.
The bodies of the nerve cells are centered in the gray matter. In the brain the gray matter may be external to white matter, e.g. cerebellum, or central to it, e.g. cerebrum. The cerebral cortex is composed of gray matter and there are some deep-seated nuclei too. In the spinal cord there is a central core of gray matter surrounded by white matter. On a cross-section of the spinal cord the gray matter follows the general pattern of the letter H.

For other uses, see Grey matter (disambiguation).

Grey matter
The formation of the spinal nerve from the dorsal and ventral roots. (Grey matter labeled at center right.)
Latin	substantia grisea
Dorlands/Elsevier	Gray matter

Grey matter (or gray matter) is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and both unmyelinated axons and myelinated axons), glial cells (astroglia and oligodendrocytes) and capillaries. Grey matter contains neural cell bodies, in contrast to white matter, which does not and mostly contains myelinated axon tracts.^[1] The color difference arises mainly from the whiteness of myelin. In living tissue, grey matter actually has a grey-brown color which comes from capillary blood vessels and neuronal cell bodies.

Contents 1 Distribution 2 Function 3 See also 4 Additional images 5 References 6 External links

Distribution

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) and spinal grey matter (anterior horn, lateral horn, posterior horn).

Function

The function of grey matter is to route sensory or motor stimulus to interneurons of the CNS in order to create a response to the stimulus through chemical synapse activity. Grey matter structures (cortex, deep nuclei) process information originating in the sensory organs or in other gray matter regions. This information is conveyed via specialized nerve cell extensions (long axons), which form the bulk of the cerebral, cerebellar, and spinal white matter.

See also

• Gray matter heterotopia
• Neuropil
• Rexed laminae
• Substantia nigra
• White matter

Additional images

Human brain right dissected lateral view

Schematic representation of the chief ganglionic categories (I to V).

References

1. ^ Purves, Dale, George J. Augustine, David Fitzpatrick, William C. Hall, Anthony-Samuel LaMantia, James O. McNamara, and Leonard E. White (2008). Neuroscience. 4th ed.. Sinauer Associates. pp. 15-16. ISBN 978-0-87893-697-7. 

External links

• Gray+matter at eMedicine Dictionary

v • d • e Histology: nervous tissue (TA A14.2.00, GA 9.849) Neurons (grey matter) Parts soma axon (axon hillock, axon terminals, axoplasm, axolemma, neurofibril/neurofilament) dendrite (Nissl body, dendritic spine, apical dendrite, basal dendrite) Types bipolar · pseudounipolar · multipolar · pyramidal · Purkinje · granule Afferent nerve fiber/ Sensory nerve GSA · GVA · SSA · SVA fibers (Ia, Ib or Golgi, II or Aβ, III or Aδ or fast pain, IV or C or slow pain) Efferent nerve fiber/ Motor nerve GSE · GVE · SVE Upper motor neuron · Lower motor neuron (α motorneuron, γ motorneuron) Termination Synapses neuropil · synaptic vesicle Interneuron (Renshaw) · neuromuscular junction · electrical synapse Sensory receptors Meissner's corpuscle · Merkel nerve ending · Pacinian corpuscle · Ruffini ending · Muscle spindle · Free nerve ending · Olfactory receptor neuron · Photoreceptor cell · Hair cell · Taste bud Support Glial cells Astrocyte (Radial glia) · Oligodendrocyte · Ependymal cells (Tanycytes) · Microglia Myelination (white matter) CNS: Oligodendrocyte PNS: Schwann cell · Neurolemma · Nodes of Ranvier/Internode · Schmidt-Lanterman incisures Related connective tissues epineurium · perineurium · endoneurium · nerve fascicle · meninges Other Posterior (Root, Ganglion, Ramus) · Anterior (Root, Ramus) · rami communicantes (Gray, White) · Preganglionic fibers · Postganglionic fibers · Lemniscus · Funiculus · Fasciculus · Decussation · Commissure Projection fibers · Association fiber · Commissural fiber peripheral nervous system navs: anat/histo/physio/dev, noncongen PNS somatic/autonomic/congen/neoplasia, symptoms+signs/eponymous, proc

v • d • e Anatomy of torso (primarily): the spinal cord (TA 14.1.02, GA 9.749) External, dorsal Posterior median sulcus · Posterolateral sulcus Grey matter/ Rexed laminae I-VI: Posterior horn I: Marginal nucleus · II: Substantia gelatinosa of Rolando · III+IV: Nucleus proprius · Spinal lamina V · Spinal lamina VI VII: Lateral horn Intermediolateral nucleus · Posterior thoracic nucleus VIII-IX: Anterior horn Interneuron · Alpha motor neuron (Onuf's nucleus) X: Other Central gelatinous substance · Gray commissure Central canal White matter somatic/ ascending (blue) Posterior/PCML: touch: Gracile · Cuneate Lateral: proprioception: Spinocerebellar (Dorsal, Ventral) · pain/temp: Spinothalamic (Lateral, Anterior) · Posterolateral (Lissauer) · Spinotectal Spinoreticular tract · Spino-olivary tract motor/ descending (red) Lateral: Corticospinal (Lateral) · Ep (Rubrospinal, Olivospinal) Anterior: Corticospinal (Anterior) · Ep (Vestibulospinal, Reticulospinal, Tectospinal) both Anterior white commissure External, ventral Anterior median fissure External, general Cervical enlargement · Lumbar enlargement · Conus medullaris · Filum terminale · Cauda equina

v • d • e Human brain: rhombencephalon, myelencephalon: medulla (TA A14.1.04, GA 9.767) Dorsal Surface Posterior median sulcus · Posterolateral sulcus · Area postrema · Vagal trigone · Hypoglossal trigone · Medial eminence Grey: Cranial nuclei afferent: GVA: VII,IX,X: Solitary/tract/Dorsal respiratory group · SVA: Gustatory nucleus efferent: GSE: XII  · GVE: IX,X,XI: Ambiguus · SVE: X: Dorsal · IX: Inferior salivatory nucleus Grey: other Gracile nucleus · Cuneate nucleus (Accessory cuneate nucleus) White: Sensory/ascending Sensory decussation  · Medial lemniscus · Inferior cerebellar peduncle (Juxtarestiform body) · Ascending dorsal longitudinal fasciculus · MLF, III, IV and VI White: Motor/descending Descending dorsal longitudinal fasciculus · MLF, III, IV and VI Ventral White: Motor/descending Motor decussation · Olivocerebellar tract · Rubro-olivary tract Grey matter Ventral respiratory group · Arcuate nucleus of medulla · Inferior olivary nucleus Surface Anterior median fissure · Antero-lateral sulcus · Olive · Pyramid Grey: Raphe/ reticular Reticular formation (Gigantocellular, Parvocellular, Ventral, Lateral, Paramedian) · Raphe nuclei (Obscurus, Magnus, Pallidus)

v • d • e Human brain, rhombencephalon, metencephalon: pons (TA A14.1.05.101-604, GA 9.785) Dorsal/ (tegmentum) Surface Cerebellopontine angle · Superior medullary velum · Sulcus limitans · Medial eminence · Facial colliculus White: Sensory/ascending Trapezoid body/VIII · Trigeminal lemniscus (Dorsal trigeminal tract, Ventral trigeminal tract) · Medial lemniscus · Lateral lemniscus MLF, III, IV and VI: Vestibulo-oculomotor fibers Anterior trigeminothalamic tract · Central tegmental tract White: Motor/descending ICP (Vestibulocerebellar tract) MLF, III, IV and VI: Vestibulospinal tract (Medial vestibulospinal tract, Lateral vestibulospinal tract) Grey: Cranial nuclei afferent: GSA: Principal V/Spinal V · VIII-c (Dorsal, Anterior)/VIII-v (Lateral, Superior, Medial, Inferior) efferent: SVE: Motor V  · VII · GSE: VI · GVE: VII: Superior salivary nucleus Other grey Apneustic center · Pneumotaxic center (Medial parabrachial nucleus) · Lateral parabrachial nucleus · Superior olivary nucleus · Caerulean nucleus Ventral/ (base) Grey Pontine nuclei White: Motor/descending Corticospinal tract · Corticobulbar tract · Corticopontine fibers MCP (Pontocerebellar fibers) Surface Basilar sulcus Other grey: Raphe/ reticular Reticular formation (Caudal, Oral, Tegmental, Paramedian) · Raphe nuclei (Median)

v • d • e Human brain: mesencephalon (midbrain) (TA A14.1.06, GA 9.800) Tectum (Dorsal) Surface Corpora quadrigemina: Inferior colliculi (Brachium of inferior colliculus), Superior colliculi (Brachium of superior colliculus) Grey matter Pretectal area White: Sensory/ascending Spinotectal tract · Central tegmental tract White: Motor/descending Tectospinal tract Peduncle (Ventral) Peduncle tegmentum White: Sensory/ascending lemnisci (Medial, Lateral) · Ascending MLF (Vestibulo-oculomotor fibers) · Spinothalamic tract · Anterior trigeminothalamic tract · Dentatothalamic tract White: Motor/descending Rubrospinal tract · Rubro-olivary tract · Descending MLF Grey: cranial nuclei GSA (V: Mesencephalic) - GSE (III: Oculomotor, IV: Trochlear) - GVE (III: Edinger-Westphal) Grey: other Periaqueductal gray/Raphe nuclei (Dorsal raphe nucleus) Ventral tegmental area • Pedunculopontine nucleus • Red nucleus riMLF Ventricular system Cerebral aqueduct Peduncle base White: Motor/descending Cerebral crus: Corticospinal tract · Corticobulbar tract · Corticopontine tract/Frontopontine fibers/Temporopontine fibers Grey: Substantia nigra Pars compacta · Pars reticulata Surface Superior cerebellar peduncles (Decussation of superior cerebellar peduncle) · Interpeduncular fossa

v • d • e Human brain, rhombencephalon, metencephalon: cerebellum (TA 14.1.07, GA 9.788) Surface anatomy Posterior lobe (Horizontal fissure) · Anterior lobe · Flocculonodular lobe (Flocculus, Nodule) Vermis: posterior (Folium, Tuber, Uvula) · anterior (Central lobule, Culmen, Lingula) Hemisphere: posterior (Biventer lobule, Cerebellar tonsil) · anterior (Alar central lobule) Vallecula of cerebellum · Primary fissure Grey matter Deep cerebellar nuclei Dentate · interposed (Emboliform, Globose) · Fastigial Cerebellar cortex Molecular layer (Stellate cell, Basket cell) Purkinje cell layer (Purkinje cell, Bergmann glia cell = Golgi epithelial cell) Granule cell layer (Golgi cell, Granule cell, Unipolar brush cell) Fibers: Mossy fibers · Climbing fiber · Parallel fiber White matter Internal Arbor vitae Peduncles Inferior (medulla): Dorsal spinocerebellar tract · Olivocerebellar tract · Cuneocerebellar tract · Juxtarestiform body (Vestibulocerebellar tract) Middle (pons): Pontocerebellar fibers Superior (midbrain): Ventral spinocerebellar tract · Dentatothalamic tract · Trigeminocerebellar fibers

v • d • e Human brain: diencephalon (TA A14.1.08, GA 9.807) Epithalamus Surface Pineal body · Habenula · Habenular trigone · Habenular commissure Grey matter Pretectal area · Habenular nuclei · Subcommissural organ Thalamus Surface Stria medullaris of thalamus · Thalamic reticular nucleus · Taenia thalami Grey matter/ nuclei paired: AN · Ventral (VA/VL, VP/VPM/VPL) · Lateral (LD, LP, Pulvinar) · Metathalamus (MG, LG) midline: MD · Intralaminar (Centromedian) · Midline nuclear group · Interthalamic adhesion White matter Mammillothalamic fasciculus · Pallidothalamic connections (Ansa lenticularis, Lenticular fasciculus, Thalamic fasciculus) · PCML (Medial lemniscus, Trigeminal lemniscus) · Spinothalamic tract · Lateral lemniscus · Dentatothalamic tract · Acoustic radiation · Optic radiation · Subthalamic fasciculus · Anterior trigeminothalamic tract Medullary laminae Hypothalamus Surface Median eminence/Tuber cinereum · Mammillary body · Infundibulum Grey matter Autonomic zones Anterior (parasympathetic/heat loss) · Posterior (sympathetic/heat conservation) Endocrine posterior pituitary: magnocellular/Paraventricular/Supraoptic (oxytocin/vasopressin) other: parvocellular/Arcuate (dopamine/GHRH) · Preoptic (GnRH) · Suprachiasmatic (melatonin) Emotion Lateral (hunger) · Ventromedial (satiety) · Dorsomedial (rage) White matter Medial forebrain bundle · Dorsal longitudinal fasciculus · Mammillothalamic fasciculus · Terminal stria Pituitary Posterior is diencephalon, but anterior is glandular Subthalamus Subthalamic nucleus · Zona incerta Ventricular system: Third ventricle recesses: (Optic recess, Infundibular recess, Suprapineal recess, Pineal recess) Hypothalamic sulcus · Tela chorioidea of third ventricle Subfornical organ Apertures: Interventricular/Monro Posterior commissure

v • d • e Human brain, cerebrum, Interior of the cerebral hemispheres - Rostral Basal ganglia and associated structures (TA A14.1.09.321-552, GA 9.832-837) Basal ganglia Grey matter Corpus striatum striatum: Putamen · Caudate nucleus lentiform nucleus: Putamen · Globus pallidus (GPe, GPi) Ventral striatum Nucleus accumbens · Olfactory tubercle · Islands of Calleja Other Amygdala · Claustrum White matter Semioval center Internal capsule (Anterior limb · Genu · Posterior limb, Optic radiation) Corona radiata · External capsule · Extreme capsule Pallidothalamic connections: Ansa lenticularis · Lenticular fasciculus · Subthalamic fasciculus · Thalamic fasciculus Rhinencephalon Grey matter Anterior olfactory nucleus · Anterior perforated substance · Olfactory bulb White matter Olfactory tract · Olfactory trigone Other basal forebrain Grey matter Substantia innominata (Basal optic nucleus of Meynert) · Nucleus of diagonal band White matter Diagonal band of Broca · Terminal stria Archicortex: Hippocampal formation/ Hippocampus anatomy Grey matter Hippocampus proper: CA1 · CA2 · CA3 · CA4 Dentate gyrus: Fascia dentata Subiculum White matter Alveus · Fimbria · Perforant path

v • d • e Human brain: telencephalon (cerebrum · cerebral cortex · cerebral hemispheres, grey matter) (TA A14.1.09.002-240, 301-320, GA 9.818-826) Frontal lobe Superolateral Precentral gyrus (Primary motor cortex, 4) Superior frontal gyrus/Frontal eye fields (6, 8, 9) · Middle frontal gyrus (46) · Inferior frontal gyrus/Broca's area (44-Pars opercularis, 45-Pars triangularis) Prefrontal cortex (Ventromedial) · Premotor cortex Precentral sulcus · Superior frontal sulcus · Inferior frontal sulcus Medial/inferior Subcallosal area · Paraterminal gyrus · Paraolfactory area · Straight gyrus · Paracentral lobule · Orbital gyri · Medial frontal gyrus Orbitofrontal cortex (10, 11, 12, 47) Olfactory sulcus · Orbital sulci · Paracentral sulcus Parietal lobe Superolateral Somatosensory cortex (Primary (1 · 2 · 3 · 43) · Secondary (5)) · Parietal operculum Parietal lobules (Superior (7l) · Inferior (40)) · Angular gyrus (39) Intraparietal sulcus Medial/inferior Paracentral lobule · Precuneus (7m) Marginal sulcus Occipital lobe Superolateral Occipital pole of cerebrum · Lunate sulcus · Transverse occipital sulcus · Lateral occipital gyrus (18, 19)) Medial/inferior Primary visual cortex (17) · Cuneus · Lingual gyrus Calcarine fissure Temporal lobe Superolateral Transverse temporal gyrus/Primary auditory cortex (41, 42) · Superior temporal gyrus (38, 22/Wernicke's area) · Middle temporal gyrus (21) · Inferior temporal gyrus (20) Superior temporal sulcus · Inferior temporal sulcus Medial/inferior Fusiform gyrus (37) Medial temporal lobe ((27 · 28 · 34 · 35 · 36)) Inferior temporal sulcus Interlobar sulci/fissures Superolateral Central (frontal+parietal) · Lateral (frontal+parietal+temporal) · Parieto-occipital · Preoccipital notch Medial/inferior Medial longitudinal · Cingulate (frontal+cingulate) · Collateral (temporal+occipital) · Callosal sulcus Limbic lobe Parahippocampal gyrus anterior (Entorhinal cortex, Perirhinal cortex) · Posterior parahippocampal gyrus · Prepyriform area Cingulate cortex/gyrus Subgenual area (25) · Anterior cingulate (24, 32, 33) · Posterior cingulate (23, 31) · Retrosplenial cortex (26, 29, 30) Hippocampal formation Hippocampal sulcus · Fimbria of hippocampus · Dentate gyrus Other Supracallosal gyrus · Uncus Insular lobe Circular sulcus of insula General Operculum · Poles of cerebral hemispheres Some categorizations are approximations, and some Brodmann areas span gyri.

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