Extrapyramidal system



Brain: Extrapyramidal system
Medulla spinalis. (Extrapyramidal tracts are labeled "2" in red, at left.)
NeuroNames ancil-623
MeSH Extrapyramidal+tracts
Dorlands/Elsevier s_33/12787420

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.

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 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 (musclar lead-pipe rigidity, bradykinesia/akinesia, resting tremor, postural instability; 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 bradykinesia 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

haloperidol, etc.).

Commonly used medications for EPS are trihexyphenidyl (Artane).exp Cannabis has also been shown to help lessen the severity of EPS.

80.60.121.4 (talk)Maria3667

See also

List of regions in the human brain

v • d • 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)

Posterior/PCML: Gracilis • Cuneatus

Lateral: Spinocerebellar (Dorsal, Ventral) • Spinothalamic (Lateral, Anterior) • Spinotectal • Posterolateral (Lissauer)

White matter: motor/descending (red)

Lateral: Corticospinal (Lateral) • Ep (Rubrospinal, Olivospinal)

Anterior: Corticospinal (Anterior) • Ep (Vestibulospinal, Tectospinal, Reticulospinal)

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
v • d • e
Brain: rhombencephalon (hindbrain)
Myelencephalon/medulla

anterior/ventral: Arcuate nucleus of medulla • Pyramid (Decussation) • Olivary body • Inferior olivary nucleus • Anterior median fissure • Ventral respiratory group

posterior/dorsal: VII,IX,X: Solitary/tract • XII, X: Dorsal • IX,X,XI: Ambiguus • IX: Inferior salivatory nucleus • Gracile nucleus/Cuneate nucleus/Accessory cuneate nucleus • Area postrema • Posterior median sulcus • Dorsal respiratory group

raphe/reticular: Sensory decussation • Reticular formation (Gigantocellular nucleus, Parvocellular reticular nucleus, Ventral reticular nucleus, Lateral reticular nucleus, Paramedian reticular nucleus) • Raphe nuclei (Obscurus, Magnus, Pallidus)

tracts: Corticospinal tract (Lateral, Anterior) • Inferior cerebellar peduncle • Olivocerebellar tract • Spinocerebellar (Dorsal, Ventral) • Spinothalamic tract • PCML (Posterior external arcuate fibers, Internal arcuate fibers, Medial lemniscus) • Extrapyramidal (Rubrospinal tract, Vestibulospinal tract, Tectospinal tract)

Metencephalon/pons

anterior/ventral: Superior olivary nucleus • Basis pontis (Pontine nuclei, Middle cerebellar peduncles)

posterior/dorsal: Pontine tegmentum (Trapezoid body, Superior medullary velum, Locus ceruleus, MLF, Vestibulocerebellar tract, V Principal Spinal & Motor, VI, VII, VII: Superior salivary nucleus) • VIII-c (Dorsal, Anterior)/VIII-v (Lateral, Superior, Medial, Inferior)

raphe/reticular: Reticular formation (Caudal pontine reticular nucleus, Oral pontine reticular nucleus, Tegmental pontine reticular nucleus, Paramedian pontine reticular formation) • Median raphe nucleus

Apneustic center • Pneumotaxic center

Metencephalon/cerebellumVermis • Flocculus • Arbor vitae • Cerebellar tonsil • Inferior medullary velum

Molecular layer (Stellate cell, Basket cell, Parallel fiber) • Purkinje cell layer (Purkinje cell) • Granule cell layer (Golgi cell) • Mossy fibers • Climbing fiber

Deep cerebellar nuclei (Dentate, Emboliform, Globose, Fastigial)
Fourth ventricleapertures (Median, Lateral) • Rhomboid fossa (Vagal trigone, Hypoglossal trigone, Obex, Sulcus limitans, Facial colliculus, Medial eminence) • Lateral recess
 
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