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In [[human anatomy]], the '''extrapyramidal system''' is a [[neural network]] located in the [[human brain|brain]] that is part of the [[motor system]] involved in the coordination of movement. The system is called "extrapyramidal" to distinguish it from the tracts of the motor cortex that reach their targets by traveling through the "pyramids" of the medulla. The pyramidal pathways ([[corticospinal]] and some [[corticobulbar]] tracts) may directly innervate motor neurons of the spinal cord or brainstem ([[anterior horn cells]] or certain cranial nerve nuclei), whereas the extrapyramidal system centers around the modulation and regulation (indirect control) of anterior horn cells.
 
In [[human anatomy]], the '''extrapyramidal system''' is a [[neural network]] located in the [[human brain|brain]] that is part of the [[motor system]] involved in the coordination of movement. The system is called "extrapyramidal" to distinguish it from the tracts of the motor cortex that reach their targets by traveling through the "pyramids" of the medulla. The pyramidal pathways ([[corticospinal]] and some [[corticobulbar]] tracts) may directly innervate motor neurons of the spinal cord or brainstem ([[anterior horn cells]] or certain cranial nerve nuclei), whereas the extrapyramidal system centers around the modulation and regulation (indirect control) of anterior horn cells.
   
Extrapyramidal tracts are chiefly found in the [[reticular formation]] of the [[pons]] and [[medulla]], and target neurons in the spinal cord involved in reflexes, locomotion, complex movements, and postural control. These tracts are in turn modulated by various parts of the central nervous system, including the [[nigrostriatal pathway]], the [[basal ganglia]], the [[cerebellum]], the [[vestibular nuclei]], and different sensory areas of the [[cerebral cortex]]. All of these regulatory components can be considered part of the extrapyramidal system, in that they modulate motor activity without directly innervating motor neurons.
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Extrapyramidal tracts are chiefly found in the [[reticular formation]] of the [[pons]] and [[medulla]], and target neurons in the spinal cord involved in reflexes, locomotion, complex movements, and postural control. These tracts are in turn modulated by various parts of the central nervous system, including the [[nigrostriatal pathway]], the [[basal ganglia]], the [[cerebellum]], the [[vestibular nuclei]], and different sensory areas of the [[cerebral cortex]]. All of these regulatory components can be considered part of the extrapyramidal system, in that they modulate [[motor activity]] without directly innervating [[motor neurons]].
   
   
==Extrapyramidal symptoms==
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==See also==
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*[[List of regions in the human brain]]
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*[[Extrapyramidal symptoms]]
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*[[Rabbit syndrome]], a rare extrapyramidal side effect
   
{{main|Extrapyramidal symptoms}}
 
The extrapyramidal system can be affected in a number of ways, which are revealed in a range of extrapyramidal symptoms such as [[akinesia]](inability to initiate movement) and [[akathisia]](inability to remain motionless).
 
 
Extrapyramidal [[adverse effect (medicine)|symptoms]] (EPS) are the various [[movement disorder]]s such as [[tardive dyskinesia]] suffered as a result of taking [[dopamine antagonist]]s, usually [[antipsychotic]] (neuroleptic) [[medication|drugs]], which are often used to control [[psychosis]], especially [[schizophrenia]]. Other [[antidopaminergic]] drugs like the [[antiemetic]] [[metoclopramide]] or the [[tricyclic antidepressant]] [[amoxapine]] can also cause extrapyramidal side effects.
 
 
===Disorders===
 
 
The best known EPS is [[tardive dyskinesia]] (involuntary, irregular muscle movements, usually in the face). Other common EPS include [[akathisia]] (restlessness), [[dystonia]] (muscular spasms of neck - [[torticollis]], eyes - [[oculogyric crisis]], tongue, or jaw; more frequent in children), drug-induced [[parkinsonism]] (muscle stiffness, shuffling gait, drooling, tremor; more frequent in adults and the elderly),
 
 
Although [[Parkinson's Disease]] is primarily a disease of the [[nigrostriatal pathway]] and not the extrapyramidal system, loss of dopaminergic neurons in the [[substantia nigra]] leads to dysregulation of the extrapyramidal system. Since this system regulates posture and skeletal muscle tone, a result is the characteristic [[dyskinesia]] of Parkinson's.
 
 
[[Extrapyramidal symptoms]] can also be caused by brain damage, as in athetotic [[cerebral palsy]], which is involuntary writhing movements caused by prenatal or perinatal brain damage.
 
 
===Treatment for extrapyramidal symptoms===
 
 
[[Anticholinergic]] drugs are used to control [[neuroleptic]]-induced EPS, although [[akathisia]] may require [[beta blocker]]s or even [[benzodiazepine]]s. If the EPS are induced by a [[typical antipsychotic]], EPS may be reduced by dose titration or by switching to an [[atypical antipsychotic]], such as [[aripiprazole]], [[ziprasidone]], [[quetiapine]], [[olanzapine]], [[risperidone]] or [[clozapine]]. These medications have a different mode of action which means they are associated with fewer extrapyramidal side effects than "conventional" antipsychotics ([[chlorpromazine]], [[haloperidol]], etc.).
 
 
Commonly used medications for EPS are [[benztropine]] (Cogentin), [[diphenhydramine]] (Benadryl), and [[trihexyphenidyl]] (Artane).
 
 
==See also==
 
[[List of regions in the human brain]]
 
   
 
{{Spinal cord}}
 
{{Spinal cord}}
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[[Category:Efferent pathways]]
 
[[Category:Efferent pathways]]
 
[[Category:Extrapyramidal tracts]]
 
[[Category:Extrapyramidal tracts]]
[[Category:Neuroleptic drugs]]
 
 
[[Category:Spinal cord]]
 
[[Category:Spinal cord]]
   

Latest revision as of 16:53, December 28, 2011

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Brain: Extrapyramidal tracts
Medulla spinalis - tracts - English
Medulla spinalis. (Extrapyramidal tracts are labeled "2" in red, at left.)
[[Image:|250px|center|]]
Latin '
Gray's subject #
Part of
Components
Artery
Vein
BrainInfo/UW ancil-623
MeSH [1]

In human anatomy, the extrapyramidal system is a neural network located in the brain that is part of the motor system involved in the coordination of movement. The system is called "extrapyramidal" to distinguish it from the tracts of the motor cortex that reach their targets by traveling through the "pyramids" of the medulla. The pyramidal pathways (corticospinal and some corticobulbar tracts) may directly innervate motor neurons of the spinal cord or brainstem (anterior horn cells or certain cranial nerve nuclei), whereas the extrapyramidal system centers around the modulation and regulation (indirect control) of anterior horn cells.

Extrapyramidal tracts are chiefly found in the reticular formation of the pons and medulla, and target neurons in the spinal cord involved in reflexes, locomotion, complex movements, and postural control. These tracts are in turn modulated by various parts of the central nervous system, including the nigrostriatal pathway, the basal ganglia, the cerebellum, the vestibular nuclei, and different sensory areas of the cerebral cortex. All of these regulatory components can be considered part of the extrapyramidal system, in that they modulate motor activity without directly innervating motor neurons.


See alsoEdit


Spinal cord

epidural space, dura mater, subdural space, arachnoid mater, subarachnoid space, pia mater, denticulate ligaments, conus medullaris, cauda equina, filum terminale, cervical enlargement, lumbar enlargement, anterior median fissure, dorsal root, dorsal root ganglion, dorsal ramus, ventral root, ventral ramus, sympathetic trunk, gray ramus communicans, white ramus communicans

grey matter: central canal, substantia gelatinosa of Rolando, reticular formation, substantia gelatinosa centralis, interneuron, anterior horn, lateral horn, posterior horn (column of Clarke, dorsal spinocerebellar tract)

white matter: anterior funiculus: descending (anterior corticospinal tract, vestibulospinal fasciculus, tectospinal tract), ascending (anterior spinothalamic tract, anterior proper fasciculus)

lateral funiculus: descending (lateral corticospinal tract, rubrospinal tract, olivospinal tract), ascending dorsal spinocerebellar tract, ventral spinocerebellar tract, spinothalamic tract, lateral spinothalamic tract, anterior spinothalamic tract, spinotectal tract, posterolateral tract, lateral proper fasciculus, medial longitudinal fasciculus

posterior funiculus: fasciculus gracilis, fasciculus cuneatus, posterior proper fasciculus


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