neurologic disorders
Overview of Movement and Cerebellar Disorders
Introduction
Voluntary movement requires complex interaction of the corticospinal (pyramidal) tracts, basal ganglia, and cerebellum (the center for motor coordination) to ensure smooth, purposeful movement without extraneous muscular contractions. Thepyramidal tractspass through the medullary pyramids to connect the cerebral cortex to lower motor centers of the brain stem and spinal cord. (caudate nucleus, putamen, globus pallidus, subthalamic nucleus, and substantia nigra) form the extrapyramidal system. They are located deep in the forebrain and rostral midbrain. The basal ganglia direct their output mainly through the thalamus to the cerebral cortex (see figure Basal ganglia ). Two main motor functions are integrated in the basal ganglia: Operational learning (motor tasks) Task selection (whether single, dual or multiple as when walking and speaking) Most neural lesions that cause movement disorders occur in the extrapyramidal system; thus, movement disorders are sometimes called extrapyramidal disorders. 