extrapyramidal motor system

n.
  1. Any of the various brain structures affecting bodily movement, excluding the motor neurons, the motor cortex, and the pyramidal tract, and including the corpus striatum, its substantia nigra and subthalamic nucleus, and its connections with the midbrain.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.