Motor Systems III: The Cerebellum Movement and Major Fiber Pathways of the Cerebellum

Abstract

The role of the cerebellum is to integrate the sensory input from the periphery to provide smooth coordinated voluntary movements. It is a laminated cortical region with four deep nuclei (dentate, fastifigial, emboliform, and interpositus) and is attached to the brain stem by three peduncles- the superior, middle and inferior cerebellar peduncles. Superior cerebellar peduncle (brachium conjunctivum) is primarily efferent and projects via the dentate, fastigial, and interpositus nucleus to the red nucleus of the midbrain and onto thalamic motor nuclei which then project onto cerebrum. The middle cerebellar peduncle (brachium pontis) is the largest cerebellar peduncle and receives input primarily from the contralateral cerebrum via deep pontine nuclei whose fibers then project onto the neocerebellum. The inferior cerebellar peduncle provides sensory input via climbing fibers from the inferior olivary nucleus of the medulla and proprioceptive mossy fibers from the spinocerebellar tract and lateral cuneate nucleus and projects onto the paleocerebellum. The juxtarestiform body lies next to the inferior cerebellar peduncle and carries ipsilateral input from the vestibular nuclei onto the flocculonodular lobe of the archicerebellum and midline vermis which are important in posture and movements.