The Cerebellum

Abstract

Basically, the cerebellum functions as a comparator and a coordinator. It compares movement intention with performance, and coordinates the equilibrium, posture, and muscle tone needed for smooth, coordinated motor activity. The cerebellum is present in all vertebrates. It receives considerable input from sensory systems, but it functions as a part of the motor system. Despite its motor function, the cerebellum contributes comparatively modest, direct connections to brainstem motor nuclei that give rise to descending spinal pathways (red nucleus, vestibular nuclei). In contrast, the cerebellum projects profusely to all major motor-control regions in the cerebrum via thalamic nuclei. As such, it is a key component for sensorimotor coordination. However, cerebellar damage typically does not produce sensory impairment or decreased muscle strength. In order to influence motor performance, the cerebellum must receive and process a great deal of information on the position and contractile state of muscles, tension within tendons, and the equilibrium of the body. Moreover, it must continuously integrate all of this data with information sent to the muscles from the motor cortex. It should be noted that the cerebellum performs these complex functions automatically, without conscious effort on the part of the individual.