Reflex activities of a target muscle are affected by motor signals from the corticospinal tract and by the influence of extrapyramidal signals.

Disorders of the extrapyramidal system

The extrapyramidal system can be affected in a number of ways, which are revealed in a range of extrapyramidal symptoms such as akinesia and akathisia.

Extrapyramidal side-effects (EPS) are the various movement disorders suffered as a result of taking antipsychotic or neuroleptic drugs, which are often used to control some symptoms of schizophrenia.

Common EPS are akathisia (restlessness), dystonia (muscular spasms of neck - torticollis, eyes - oculogyric crisis, tongue, or jaw; more frequent in children), drug-induced Parkinsonian syndrome (muscle stiffness, shuffling gait, drooling, tremour; more frequent in adults and the elderly), and tardive dyskinesia (involuntary, irregular muscle movements, usually in the face).

Anticholinergic drugs are used to control neuroleptic-induced EPS, although akathisia may require beta blockers or even benzodiazepines.