Key points

■ The cerebellum receives subconscious proproprioceptive input from Golgi tendon organs and muscle spindles and the hair cells of the vestibular apparatus.

■ It coordinates tone and movement of the head, body and limbs, by modulating activity of UMNs affecting agonist and antagonist muscles.

■ It feeds back proprioceptive information to motor planning centres of the forebrain and is involved in setting the postural platform.

■ The grey matter consists of a three-layered cortex (granule cells, Purkinje cells and molecular layer) and three pairs of deep cerebellar nuclei.

■ The white matter forms the arbor vitae and is connected to the brainstem by three pairs of cerebellar peduncles.

■ The ability of a neonatal animal to move correlates with the amount of cerebellar development at birth.

■ Deep cerebellar nuclei facilitate somatic UMNs and are inhibited by the only efferents from the cerebellar cortex, the gabaminergic Purkinje cells.

■ Spinocerebellar pathways, conveying subconscious proprioception, comprise two neurons, compared with the three-neuron pathway involved in conscious proprioception.

■ Clinical signs of cerebellar dysfunction may include ataxia, hypermetria, spasticity and tremor, but not paresis.

‘The cerebellum is the head ganglion of the proprioceptive system. ’

(Charles Sherrington, 1947)

The cerebellum, derived from the Latin meaning ‘little brain’, comprises just 10% of the brain’s volume but contains at least 50% of its neurons. Although it develops as a dorsal outgrowth from the metencephalon, it is not part of the brainstem. The cerebellum receives subconscious proprioceptive information from the body, limbs and head. That sensory input is used to modify and coordinate muscle action for posture and movement.