Superior cerebellar peduncle
Pedunculus cerebellaris superior
A paired band of white matter that joins the cerebellum to the midbrain, carrying most of the cerebellum's output upward.
At a glance
- English
- Superior cerebellar peduncle
- Latin (TA2)
- Pedunculus cerebellaris superior
- System
- Brain and spinal cord
- Region
- Head
- Side
- Paired, left and right
About the superior cerebellar peduncle
The superior cerebellar peduncle, also called the brachium conjunctivum, is one of the paired stalks that attach the cerebellum to the brainstem. It leaves the upper, medial white matter of each cerebellar hemisphere, tucked under the upper surface of the cerebellum, and runs forward and upward to enter the midbrain below the inferior colliculus. The two peduncles are joined by a thin sheet, the superior medullary velum. In their lower course they form the upper side walls of the fourth ventricle; as they rise they come together over its back and help form its roof.
Most of its fibres are efferent. They arise in the deep cerebellar nuclei: from the dentate nucleus, the largest, run cerebellothalamic fibres, and from the emboliform and globose (interposed) nuclei run cerebellorubral fibres. In the lower midbrain, level with the inferior colliculi, these fibres cross the midline in the decussation of the superior cerebellar peduncles, sometimes called the horseshoe commissure of Wernekinck. They then reach the red nucleus of the opposite side or pass around and through it to the ventral lateral nucleus of the thalamus, which projects to the motor cortex.
A smaller number of fibres travel in the opposite direction into the cerebellum. The most important is the anterior (ventral) spinocerebellar tract, which climbs through the pons and turns back along the peduncle. Tectocerebellar fibres from the colliculi, trigeminal fibres and noradrenergic fibres from the locus coeruleus also enter this way.
Because the outflow crosses in the midbrain and the descending motor paths cross again lower down, cerebellar damage affects the same side of the body. A lesion of the peduncle below the decussation causes clumsiness and intention tremor on the same side, whereas one above it gives signs on the opposite side. Multiple sclerosis plaques here can cause severe tremor of the arm.
Function and supply
- Function
- Carries the main output of the cerebellum to the opposite red nucleus and thalamus for coordinating movement, and brings some spinal and brainstem input into the cerebellum.
- Blood supply
- Branches of the superior cerebellar artery.
Anthromica
See the superior cerebellar peduncle where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
