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Information about White Matter

The formation of the spinal nerve from the dorsal and ventral roots. (White matter labeled at right.)
Latinsubstantia alba
Dorlands/Elsevier s_27/12766685
White matter is one of the three main solid components of the central nervous system designated by color. The other two are gray matter and substantia nigra.

Structure

It is composed of myelinated nerve cell processes, or axons, which connect various gray matter areas (the locations of nerve cell bodies) of the brain to each other and carry nerve impulses between neurons.

Cerebral and spinal white matter do not contain dendrites, which can only be found in gray matter along with neural cell bodies and shorter axons.

Function

The white matter is the tissue through which messages pass between different areas of gray matter within the nervous system. Using a computer network as an analogy, the gray matter can be thought of as the actual computers themselves, whereas the white matter represents the network cables connecting the computers together. 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 as the insulation is important for allowing the messages to pass quickly from place to place.

The brain in general (and especially a child's brain) can adapt to white matter damage by finding alternative routes which bypass the damaged areas of white matter and can therefore maintain good connections between the various areas of gray matter.

Unlike gray matter, which peaks in development in a persons twenties, the white matter continues to develop and peaks in late middle age.

Location

White matter forms the bulk of the deep parts of the brain and the superficial parts of the spinal cord. Aggregates of grey matter such as the basal ganglia (caudate nucleus, putamen, globus pallidus, subthalamic nucleus, nucleus accumbens) and brain stem nuclei (red nucleus, substantia nigra, cranial nerve nuclei) are spread within the cerebral white matter.

The cerebellum is structured in a similar manner as the cerebrum, with a superficial mantle of cerebellar cortex, deep cerebellar white matter (called the "arbor vitae") and aggregates of grey matter surrounded by deep cerebellar white matter (dentate nucleus, globose nucleus, emboliform nucleus, and fastigial nucleus). The fluid-filled cerebral ventricles (lateral ventricles, third ventricle, cerebral aqueduct, fourth ventricle) are also located deep within the cerebral white matter.and suppl

Types of astrocytes

In 1983, M. C. Raff et al. discovered that tissue samples originating from rat optic nerve contained two morphologically distinct types of astrocytes.
  • So-called "Type 1 astrocytes" had a fibroblast appearance and resided in both gray matter and white matter.
  • "Type 2 astrocytes" has a neuron-like appearance and resided in white matter alone (Sherman, Chris).

Clinical relevance

Multiple Sclerosis is one of the most common disease which affects white matter. In MS lesions, the myelin shield around the axons has been destroyed by inflammation.

Changes in white matter known as amyloid plaques are associated with Alzheimer's disease and other neurodegenerative diseases. White matter injuries ("axonal shearing") may be reversible, while gray matter regeneration is less likely.

Notes

External links

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Histology: nervous tissue
Neurons (gray matter)soma, axon (axon hillock, axoplasm, axolemma, neurofibril/neurofilament), dendrite (Nissl body, dendritic spine)
types (bipolar, pseudounipolar, multipolar, pyramidal, Purkinje, granule)
Afferent nerve/Sensory nerve/Sensory neuronGSA, 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/Motor nerve/Motor neuronGSE, GVE, SVE, Upper motor neuron, Lower motor neuron (Aα motorneuron, Aγ motorneuron)
Synapsesneuropil, synaptic vesicle, neuromuscular junction, electrical synapse - Interneuron (Renshaw)
Sensory receptorsFree nerve ending, Meissner's corpuscle, Merkel nerve ending, Muscle spindle, Pacinian corpuscle, Ruffini ending, Olfactory receptor neuron, Photoreceptor cell, Hair cell, Taste bud
Glial cellsastrocyte, oligodendrocyte, ependymal cells, microglia, radial glia
Myelination (white matter)Schwann cell, oligodendrocyte, nodes of Ranvier, internode, Schmidt-Lanterman incisures, neurolemma
Related connective tissuesepineurium, perineurium, endoneurium, nerve fascicle, meninges
 •  • [ e]
Anatomy of torso (primarily): the spinal cord
Spinal nerveDorsal (Root, Ganglion, Ramus) • Ventral (Root, Ramus) • Sympathetic trunk • rami communicantes (Gray, White)
Gray matter/Rexed laminaePosterior horn (Column of Clarke, Substantia gelatinosa of Rolando, Nucleus proprius) • Lateral horn • Anterior horn • Central canal/Substantia gelatinosa centralis
White matter: somatic/ascending (blue)
White matter: motor/descending (red)
LayersEpidural space • Dura mater • Subdural space • Arachnoid mater • Subarachnoid space • Pia mater
Other structuresDenticulate ligaments • Conus medullaris • Cauda equina • Filum terminale • Cervical enlargement • Lumbar enlargement • Anterior median fissure
Latin}}} 
Official status
Official language of: Vatican City
Used for official purposes, but not spoken in everyday speech
Regulated by: Opus Fundatum Latinitas
Roman Catholic Church
Language codes
ISO 639-1: la
ISO 639-2: lat
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Elsevier, the world's largest publisher of medical and scientific literature, forms part of the Reed Elsevier group. Based in Amsterdam, the company has substantial operations in the UK, USA and elsewhere.
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The central nervous system (CNS) represents the largest part of the nervous system, including the brain and the spinal cord. Together with the peripheral nervous system, it has a fundamental role in the control of behavior.
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"Gray Matter"
Author Stephen King
Language English
Genre(s) Horror, science fiction
Published in Cavalier (1st release) ,
Night Shift,
Arbour House Necropolis
Publication type Magazine
Media type Print
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The substantia nigra (Latin for "black substance", Soemering) or locus niger is a heterogeneous portion of the midbrain, separating the pes (foot) from the tegmentum (covering), and a major element of the basal ganglia system.
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Myelin is an electrically insulating phospholipid layer that surrounds the axons of many neurons. It is an outgrowth of glial cells: Schwann cells supply the myelin for peripheral neurons while oligodendrocytes supply it to those of the central nervous system.
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Neurons (also known as neurones and nerve cells) are electrically excitable cells in the nervous system that process and transmit information. In vertebrate animals, neurons are the core components of the brain, spinal cord and peripheral nerves.
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axon or nerve fiber, is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma.

Anatomy


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In animals, the brain or encephalon (Greek for "in the skull"), is the control center of the central nervous system, responsible for behavior. The brain is located in the head, protected by the skull and close to the primary sensory apparatus of vision, hearing,
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An action potential is a "spike" of electrical discharge that travels along the membrane of a cell. Action potentials are an essential feature of animal life, rapidly carrying information within and between tissues. They also occur in some plants.
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The telencephalon (IPA: /tɛlɛnˈsɛfəlɑn/) is the name for the forebrain, a large region within the brain to which many functions are attributed.
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For the dendritic crystal structure, see .


Dendrites (from Greek dendron, “tree”) are the branched projections of a neuron that act to conduct the electrical stimulation received from other neural cells to the cell body, or
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"Gray Matter"
Author Stephen King
Language English
Genre(s) Horror, science fiction
Published in Cavalier (1st release) ,
Night Shift,
Arbour House Necropolis
Publication type Magazine
Media type Print
..... Click the link for more information.
The soma, or perikaryon, is the bulbous end of a neuron, containing the cell nucleus. It is also known as the cell body. The word soma is Greek, meaning "body"; the soma of a neuron is often called the "cell body".
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spinal chord is a thin, tubular bundle of nerves that is an extension of the central nervous system from the brain and is enclosed in and protected by the bony vertebral column.
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The basal ganglia (or basal nuclei) are a group of nuclei in the brain interconnected with the cerebral cortex, thalamus and brainstem. Mammalian basal ganglia are associated with a variety of functions: motor control, cognition, emotions and learning.
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The caudate nucleus is a nucleus located within the basal ganglia of the brains of many animal species. The caudate, originally thought to primarily be involved with control of voluntary movement, is now known to be an important part of the brain's learning and memory system.
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putamen is a structure in the middle of the brain, which, together with the caudate nucleus forms the dorsal striatum.

The putamen is a portion of the basal ganglia that forms the outermost part of the lenticular nucleus.
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The globus pallidus (Latin for "pale globe") is a sub-cortical structure of the brain. It is a major element of the basal ganglia system. In this system, it is a major element of the basal ganglia core, consisting of the striatum and its direct targets: globus pallidus and
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The subthalamic nucleus is a small lens-shaped nucleus in the brain where it is a part of the basal ganglia system. As suggested by its name, the subthalamic nucleus is located ventral to the thalamus. It is also dorsal to the substantia nigra and medial to the internal capsule.
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The nucleus accumbens (NAcc), also known as the accumbens nucleus or as the nucleus accumbens septi (Latin for nucleus leaning against the septum), is a collection of neurons within the forebrain, located where the head of the caudate and the anterior
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The red nucleus is a structure in the rostral midbrain involved in motor coordination. It comprises a caudal magnocellular and a rostral parvocellular part.

Function

In animals without a significant corticospinal tract, gait is mainly controlled by the red nucleus.
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The substantia nigra (Latin for "black substance", Soemering) or locus niger is a heterogeneous portion of the midbrain, separating the pes (foot) from the tegmentum (covering), and a major element of the basal ganglia system.
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Cranial nerves are nerves that emerge directly from the brain in contrast to spinal nerves which emerge from segments of the spinal cord. Although thirteen cranial nerves in humans fit this description, twelve are conventionally recognized.
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The cerebellum (Latin: "little brain") is a region of the brain that plays an important role in the integration of sensory perception and motor output. Many neural pathways link the cerebellum with the motor cortex—which sends information to the muscles causing them
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The arbor vitae (Latin for "Tree of Life") is the cerebellar white matter, so called for its branched, tree-like appearance.

External links

  • Bioweb at UWLAX aplab
  • BrainMaps at UCDavis Cerebellum

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The Dentate nucleus is located within the deep white matter of each cerebellar hemisphere. It is the largest of the four deep cerebellar nuclei, the others being the fastigial nucleus and the interposed nucleus (globose and emboliform nuclei combined).
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The globose nucleus is an elongated mass, directed antero-posteriorly, and placed medial to the emboliform nucleus.

This article was originally based on an entry from a public domain edition of Gray's Anatomy.
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The emboliform nucleus lies immediately to the medial side of the nucleus dentatus, and partly covering its hilus. It is one among the four pairs of cerebellar nuclei, which are from lateral to medial: the dentate, interposed (emboliform and globose), and fastigial nuclei.
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fastigial nucleus or nucleus fastigii refers specifically to the concentration of gray matter nearest to the middle line at the anterior end of the superior vermis, and immediately over the roof of the fourth ventricle, from which it is separated by a thin layer of white
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