Superior cerebellar peduncle

Last revised by Dr Francis Deng on 20 Dec 2020

The superior cerebellar peduncles, also known as the brachium conjunctivum, are paired white matter fiber tracts that connect the cerebellum with the midbrain. The superior cerebellar peduncle contains vital afferent and efferent fibers including cerebellothalamic, cerebellorubral and ventrospinocerebellar tracts.

The superior cerebellar peduncles decussate centrally (decussation of Wernekinck) in the ventral midbrain at the level of the inferior colliculi. Diffusion tensor imaging (DTI) enables depiction of the superior cerebellar peduncle decussation and on the color-coded fractional anisotropy map this is seen as a red dot in the ventral midbrain (conventionally, red denote transversely-oriented fibers).

The thin superior medullary velum is suspended between the two peduncles.

The superior cerebellar peduncles receive their arterial blood supply through branches of the superior cerebellar artery.

Clinically superior cerebellar peduncular decussation is relevant in congenital anomalies of the posterior fossa in particular in Joubert syndrome where the superior cerebellar peduncle decussation is absent, giving the characteristic molar tooth sign.

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Cases and figures

  • Figure 1: cerebellar peduncles (Gray's illustration)
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  • Figure 2: cerebellar peduncles (Gray's illustration)
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  • Figure 3: decussation of fibers in the brainstem (Gray's illustration)
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  • Figure 4: decussation of SCP on DTI
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