Anatomy of the cerebellum major part of the cerebellum by mass, but in other vertebrates, it is typically the spinocerebellum. In amphibians, lampreys, and hagfish the cerebellum is little developed; in the latter two groups it is barely distinguishable from the brain-stem. Although the spinocerebellum is present in these groups, the primary structures are small paired nuclei corresponding to the vestibulocerebellum. The cerebellum follows the general groups-of-three pattern found in anatomy, with three major input and output cerebellar peduncles (fiber bundles). These are the superior (brachium conjunctivum), middle (brachium pontis), and inferior (restiform and juxtarestiform bodies) cerebellar peduncles. There are three sources of input
Anatomy of the cerebellum pathway transmits signals that inform the cerebellum about the movement in progress and the upcoming movement. This helps the continuous adjustment of motor activity. The initiation of the movement is relayed to cerebellum via the corticoreticulocerebellar pathway. Those synapse ipsilaterally in the reticular formation, then via the inferior and middle peduncles into the cerebellar vermis. The motor cortex and somatosensory cortex projects onto the ipsilateral inferior and accessory olivary nuclei, then forming the olivocerebellar tract. Cortico-olivary fibers synapse bilaterally in the inferior olivary nucleus. The order is preserved in the olivocerebellar tract projections onto the ‘body maps’ in the contralateral