This chapter provides an overview of the basic features of the macroscopic and microscopic anatomy, physiology and potential functioning of the human cerebellum. Apart from its certain role in movement control by coordinating complex movements, additional hypotheses on the role of the cerebellum in adapting, conditioning and learning, or automating, movements are described. Views that portray the cerebellum as a timing device or as a structure that serves to optimize the quality of sensory input are also mentioned. As the cerebellum not only participates in movement control, understanding and appreciating its functioning may also explain its role in cognition, emotion, and autonomic functions. Finally, cerebellar disorders and clinical manifestations of cerebellar dysfunction in movement control are discussed.

The motor thalamus is a complex system made of several subnuclei that together play a pivotal role in the planning and execution of movement. Some subnuclei were considered to form the “classical motor thalamus” (ventroanterior, ventrolateral, and ventromedial nuclei), and other thalamic subnuclei (centrolateral, parafascicular, and centromedian nuclei) innervate sensorimotor cortical areas. The cerebellum innervates all motor thalamus nuclei, with axons from all four different cerebellar nuclei. Decades of neuroanatomical tracer experiments have revealed that the cerebellar nuclei axons form excitatory synapses in the thalamus, thus creating somototopically organized cerebello-thalamo-cortical networks. Electrophysiological data at the synaptic, cellular, and network levels reveal how the action-potential firing patterns of cerebellar and cerebral cortical inputs are integrated in the motor thalamus to synergistically drive its output. In the current chapter, we provide a review of the anatomical and electrophysiological data and share our opinion on how the cerebellum regulates the precise timing of thalamo-cortical activity. We conclude our chapter with a discussion of the role of the cerebello-thalamo-cortical tract in the pathophysiology and treatment of movement disorders, autism spectrum disorders, and epilepsy.