Superior Cerebellar Peduncle

pedunculus cerebellaris superior

The superior cerebellar peduncle is the main output pathway of the cerebellum, connecting it to the midbrain. Its fibres come mostly from the dentate and interposed nuclei, cross the midline in the lower midbrain and end in the opposite red nucleus and thalamus.

Anatomical Data

Structure & Connections

Location	Paired bands forming the upper side walls of the fourth ventricle, running from the cerebellum up into the midbrain tegmentum, joined by the superior medullary velum
Parts	Dentatorubrothalamic fibres Decussation of the superior cerebellar peduncles Ventral spinocerebellar tract (incoming fibres)
Connections	Dentate and interposed nuclei (origin) Contralateral red nucleus Contralateral ventral lateral thalamus Ventral spinocerebellar tract (input to the cerebellum)
Blood Supply	Superior cerebellar artery

Biomechanics

Function & Actions

Carries cerebellar coordination signals to the opposite thalamus and red nucleus so they can influence motor cortex and limb movement.

Clinical Relevance

Clinical Notes

Lesions of the superior cerebellar peduncle cause severe ipsilateral limb ataxia and tremor if below the decussation and contralateral if above it. Bilateral lesions at the decussation in the midbrain cause Wernekinck commissure syndrome with bilateral ataxia. Atrophy of the superior cerebellar peduncle on MRI supports the diagnosis of progressive supranuclear palsy.

Pathology

Common Injuries & Conditions

Wernekinck Commissure Syndrome

A caudal midbrain lesion at the decussation of the superior cerebellar peduncles causing bilateral cerebellar ataxia, sometimes with eye movement problems.

Superior Cerebellar Peduncle Atrophy in PSP

Shrinkage of the peduncle seen on MRI in progressive supranuclear palsy, helping distinguish it from Parkinson disease.

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