The 3rd subdivision of the cerebellum is the cerebrocerebellum. This system consists of connections from the cerebral cortex (predominantly motor) to the cerebellar hemispheres then back to the cerebral cortex. This system is important in motor planning. Dysfunction of the cerebellar hemispheres results in ataxia of speech (scanning dysarthria) and ataxia of the extremities (appendicular ataxia). It is important to remember that ataxia caused by disease of the cerebellar hemispheres will be ipsilateral to the dysfunctional hemisphere. The findings of appendicular ataxia are hypotonia, decomposition of movement, dysmetria, and difficulty with rapid alternating movements (dysdiadochokinesia). NeuroLogic Exam has been supported by a grant from the Slice of Life Development Fund at the University of Utah, the Department of Pediatrics and the Office of Education at the University of Nebraska Medical Center. Viewing the video requires installation of the free QuickTime Plug-in. Both English & Spanish audio & captions are available in this video.