The cerebellum is the part of the hindbrain that lies within the posterior cranial fossa, inferior to the occipital lobes and dorsal to the brainstem. It consists of three lobes (the anterior, posterior, and flocculonodular lobe). Functionally, it is divided into three zones. These are the cerebrocerebellum (the lateral zones), which receives sensory information from the cerebral cortex and is responsible for the planning of movements that are just about to occur (motor planning); the spinocerebellum (the vermis and intermediate zones), which receives proprioceptive information from the dorsal columns of the spinal cord and is responsible for the coordination of movements (motor execution); and the vestibulocerebellum (the flocculonodular lobe), which receives information from the vestibular nuclei and visual cortex and is responsible for balance and ocular movements. The cerebellar cortex transmits the information received from the three afferents (i.e., the cerebrum, spinal cord, and vestibular nuclei) to the four cerebellar nuclei (dentate, emboliform, globose, and fastigial) within the inner white matter. The cerebellar nuclei send efferent impulses to the thalamus, red nucleus, and reticular formation to execute cerebellar functions. The cerebellar tracts travel through the cerebellar peduncles.
- Control of balance and ocular movements
- Planning of movements that are about to occur
- Coordination of complex and sequential movements
- Maintenance of muscle tone
- The 2 hemispheres of cerebellum are separated in the midline by the cerebellar vermis.
- The cerebellar tonsil is an ovoid lobule located on the inferomedial aspect of each cerebellar hemisphere, above the foramen magnum
- Sulci and fissures further divide the cerebellum into lobes (see “Lobes and fissures” below)
Lobes and fissures
- Three lobes
- Main fissures
- Three pairs of brain stem. connect the cerebellum to the
- Afferent and efferent cerebellar tracts travel through the peduncles to and from the ipsilateral cerebellar cortex.
|Superior cerebellar peduncles (SCP)|
|Middle cerebellar peduncles (MCP)|| |
|Inferior cerebellar peduncles (ICP)|| |
Cerebellar lesions cause neurological deficits on the ipsilateral side!
Vasculature of the cerebellum 
- Basilar artery
- Vertebral artery
- Veins: the cerebellar veins drain into the and the .
|Zones of cerebellum|
|Corresponding cortex|| || |
|Function|| || |
|Effect of lesions|
For further information on the effects of cerebellar lesions, see “Clinical features” in.
A tip to remember the symptoms of cerebellar lesions: lesions of the medial part of cerebellum (i.e., vermis, flocculonodular lobe, and corresponding deep nuclei) affect medial structures (i.e., axial and proximal limb musculature), resulting in symptoms including truncal ataxia and nystagmus. Lesions of the lateral parts of cerebellum (i.e., the hemispheres) affect lateral structures (distal limb musculature), resulting in symptoms such as ipsilateral limb ataxia.
Cerebellar cortex 
- Receives afferent inputs from the cerebrum, spinal cord, and vestibular nuclei
- Sends neural impulses to the
- Composed of 5 types of neuronal cells, densely packed and arranged in 3 layers
- The cortex is primarily an inhibitory structure; all cerebellar cells except granule cells are inhibitory.
Purkinje cell layer
(middle layer or ganglionic layer)
Granular layer of the cerebellum
- Composed of climbing fibers, mossy fibers, Purkinje cell axons, and the deep cerebellar nuclei
- Mossy fibers : afferent axons from the cerebral cortex, pons, spinal cord, and vestibular nuclei to the cerebellum. Terminate on granule cells → send excitatory stimuli to the Purkinje cells.
- Climbing fibers: afferent axons from the inferior olivary nuclei of the medulla → terminate on Purkinje cells
- Four deep cerebellar nuclei (from lateral to medial): dentate, emboliform, globose, and fastigial nucleus
- For information on the function and neural pathways of the cerebellar medulla, see “Cerebellar tracts” below.
Purkinje cells are inhibitory!
Afferent cerebellar tracts (input) 
- Afferent tracts arise from three main sources: the cerebral cortex, the spinal cord, and the vestibular nerve.
- Afferent tracts are excitatory and travel to the cerebellum via mossy fibers and climbing fibers.
- Afferent tracts travel mainly through the inferior and middle cerebellar peduncles.
|Afferent cerebellar tracts|
|Cerebral cortex|| || |
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Efferent cerebellar tracts 
- Efferent tracts originate from the four deep cerebellar nuclei and travel mainly via the superior cerebellar peduncle.
- The tracts of the fastigial nucleus travel via the inferior cerebellar peduncle.
|Rubrospinal tract|| || |
|Cerebellovestibular tract|| |
The deep nuclei are the only output from the cerebellum.