“Extrapyramidal” System

“Extrapyramidal” System

The term extrapyramidal motor system is widely used in clinical circles to denote all those portions of the brain and brain stem that contribute to motor control but are not part of the direct corticospinal-pyramidal system. These include pathways through the basal ganglia, the reticular formation of the brain stem, the vestibular nuclei, and often the red nuclei. This is such an all-inclusive and diverse group of motor control areas that it is difficult to ascribe specific neurophysiologic func-tions to the so-called extrapyramidal system as a whole. For this reason, the term “extrapyramidal” is being used less often both clinically and physiologically.