Cerebellum cerebellum may be absent. The inherited neurological disorders Machado–Joseph disease, ataxia telangiectasia, and Friedreich's ataxia cause progressive neurodegeneration linked to cerebellar loss. Congenital brain malformations outside the cerebellum can, in turn, cause herniation of cerebellar tissue, as seen in some forms of Arnold–Chiari malformation. Other conditions that are closely linked to cerebellar degeneration include the idiopathic progressive neurological disorders multiple system atrophy and Ramsay Hunt syndrome type I, and the autoimmune disorder paraneoplastic cerebellar degeneration, in which tumors elsewhere in the body elicit an autoimmune response that causes neuronal loss in the cerebellum. Cerebellar atrophy can result from an acute
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