Basal ganglia: A region consisting of 3 clusters of neurons (called the caudate nucleus, putamen, and the globus pallidus) located at the base of the brain that are responsible for involuntary movements such as tremors, athetosis, and chorea. The basal ganglia are abnormal in a number of important neurologic conditions including Parkinson disease and Huntington disease. The term "basal ganglia" refers to the fact that this region is in the "basement" of the brain.
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