In anatomy, the extrapyramidal system is a part of the motor system network causing involuntary actions. 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 tracts ( corticospinal tract and corticobulbar tracts) may directly innervate motor neurons of the spinal cord or brainstem ( anterior (ventral) horn cells or certain cranial nerve nuclei), whereas the extrapyramidal system centers on the modulation and regulation (indirect control) of anterior (ventral) horn cells. Extrapyramidal tracts are chiefly found in the

reticular formation The reticular formation is a set of interconnected nuclei that are located throughout the brainstem. It is not anatomically well defined, because it includes neurons located in different parts of the brain. The neurons of the reticular formation ...

of the pons and medulla, and target lower motor neurons in the spinal cord that are 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 cerebellum (Latin for "little brain") is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as or even larger. In humans, the cerebel ...

, 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. The extrapyramidal tracts include parts of the following: *

rubrospinal tract The rubrospinal tract is a part of the nervous system. It is a part of the lateral indirect extra-pyramidal tract. Structure In the midbrain, it originates in the magnocellular red nucleus, crosses to the other side of the midbrain, and descend ...

*pontine reticulospinal tract *medullary reticulospinal tract * lateral vestibulospinal tract * tectospinal tract

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{{DEFAULTSORT:Extrapyramidal System Central nervous system All articles with unsourced statements Motor system

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