Cerebellar hemisphere

Hemispherium cerebelli

NervousOrgansHeadLeft and right

View left in 3D View right in 3D

What it is
One of the two large lateral lobes of the cerebellum in the posterior cranial fossa, under the tentorium and behind the brainstem. Its surface is folded into thin parallel leaves (folia) separated by fissures; the horizontal fissure runs round its margin.
Function
Coordinates movement on the SAME side of the body: timing, smoothness, balance and motor learning, comparing intended with actual movement.
Size
Cerebellum about 10 cm wide, 5 cm high and 6 cm deep; ~150 g, 10% of brain weight but over half of all its neurons
Clinical note
A hemisphere lesion causes ipsilateral clumsiness: overshooting (dysmetria), intention tremor and inability to do rapid alternating movements (dysdiadochokinesia).

Nearby nervous structures C1 spinal nerve, Cerebellar vermis, Cerebellar white matter (arbor vitae), Facial nerve (CN VII), trunk, Fourth ventricle, Tentorium cerebelli, Trigeminal nerve (CN V), root, Trochlear nerve root (CN IV), Vestibulocochlear nerve (CN VIII), Vestibulocochlear nerve root (CN VIII)