extrapyramidal

extrapyramidal /ex·tra·py·ram·i·dal/ (-pi-ram´i-d'l) outside the pyramidal tracts; see under system.

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ex·tra·py·ram·i·dal (kstr-p-rm-dl)

adj.

Relating to or involving neural pathways situated outside or independent of the pyramidal tracts.

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extrapyramidal

outside the pyramidal tracts.

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extrapyramidal disease, extrapyramidal syndrome

any of a group of clinical disorders marked by abnormal involuntary movements, alterations in muscle tone, and postural disturbances.

extrapyramidal motor system

see extrapyramidal system (below).

extrapyramidal system

a functional, rather than anatomical, unit comprising the nuclei and fibers (excluding those of the pyramidal tract) involved in motor activities; they control and coordinate especially the postural, static, supporting and locomotor mechanisms. It includes the corpus striatum, subthalamic nucleus, substantia nigra and red nucleus, along with their interconnections with the reticular formation, cerebellum and cerebrum; some authorities include the cerebellum and vestibular nuclei. Called also extrapyramidal motor system.