All parts of the brain › Cerebellar peduncles

Where are the cerebellar peduncles?

The cerebellar peduncles are three paired bundles of nerve fibres that join the cerebellum to the back of the brainstem: the superior peduncle to the midbrain, the middle peduncle to the pons and the inferior peduncle to the medulla oblongata. They are the cerebellum’s three major input and output routes. [1][2]

The 3D brain needs JavaScript. The text below still says where the cerebellar peduncles are and what they do.

Lit: the whole cerebellum, midbrain, pons and medulla oblongata.

Slice

The cerebellum, midbrain, pons and medulla oblongata are lit together; the cerebellar peduncles are not drawn on their own. The side (sagittal) slice button cuts through them. Drag to turn, pinch or scroll to zoom, tap any part to name it; .

Not a separate shape in this atlas; lit: the part that holds it. Lit: the whole cerebellum, midbrain, pons and medulla oblongata. The three peduncles lie between these four lit parts: each pair joins the cerebellum to one level of the brainstem. The BodyParts3D model draws the cerebellum, midbrain, pons and medulla oblongata but no peduncle, so nothing is drawn at a guessed point; the buttons under “Each one lit with the two parts it joins” light one peduncle’s two parts at a time. [1]

Lit here: the cerebellum and the midbrain and the pons and the medulla oblongata, the parts the cerebellar peduncles lie between — see each on its own page.

Next to it, each lit on its own page: fourth ventricle.

Each one lit with the two parts it joins

Superior cerebellar peduncle (brachium conjunctivum), cerebellum to midbrain: mainly output. It carries the cerebellothalamic tract from the dentate nucleus to the thalamus of the opposite side and the cerebellorubral tract to the red nucleus; these fibres cross the midline at the level of the inferior colliculi. Its main incoming tract is the ventral spinocerebellar tract. [3]
Middle cerebellar peduncle (brachium pontis), cerebellum to pons: the largest of the three and almost entirely input. Its fibres start in the pontine nuclei, cross to the other side within the pons and end in the opposite cerebellar hemisphere, carrying information from the cerebrum and the pons. [4]
Inferior cerebellar peduncle (restiform body plus the smaller juxtarestiform body), cerebellum to medulla oblongata: the smallest of the three. It brings in the dorsal spinocerebellar and cuneocerebellar tracts (unconscious body position from the trunk, legs, arms and neck), olivocerebellar fibres from the inferior olive of the opposite side and vestibular input, and carries output from Purkinje cells out to the vestibular nuclei. [5]

Where it is

Together they form the side walls of the fourth ventricle in a diamond: the middle peduncles make its side corners, the superior peduncles its upper edges and the inferior peduncles its lower edges. [1]
The superior peduncle leaves the upper, inner part of the white matter of each cerebellar hemisphere and runs up under the top of the cerebellum; the two are joined by the superior medullary velum and disappear under the inferior colliculi. [3]
The inferior peduncle is a thick rope-like strand on the back of the upper medulla oblongata, between the lower part of the fourth ventricle and the roots of the glossopharyngeal and vagus nerves. [5]
The trigeminal nerve leaves the side of the pons very close to the middle peduncle. [4]

What it does

Most of the cerebellum’s output first synapses in the deep cerebellar nuclei and then leaves through the peduncles. [2]
Input far outweighs output: the middle peduncle is almost all incoming fibres and the inferior mostly incoming, while the superior is the main way out. [4][5][3]
The inferior peduncle’s inputs serve balance and posture: it joins body-position signals from the spinal cord with vestibular signals from the inner ear’s balance organs. [5]

Connections

Blood supply: the superior peduncles from the superior cerebellar artery, the middle from the anterior inferior cerebellar artery with small basilar branches, the inferior from the posterior inferior cerebellar artery. [2][4]

Other names

Not the cerebral peduncles: those are the two large stalks at the front of the midbrain carrying descending tracts from the cerebral cortex, while the cerebellar peduncles join the cerebellum at the back of the brainstem. [6][1]

Size

The model has no shape for the cerebellar peduncles itself, so it is not measured here. The cerebellum that holds it measures about 56 mm front to back, 53 mm top to bottom and 106 mm side to side on this model (the box it fits in, not its volume). [7]
The model has no shape for the cerebellar peduncles itself, so it is not measured here. The midbrain that holds it measures about 29 mm front to back, 17 mm top to bottom and 29 mm side to side on this model (the box it fits in, not its volume). [7]
The model has no shape for the cerebellar peduncles itself, so it is not measured here. The pons that holds it measures about 34 mm front to back, 29 mm top to bottom and 42 mm side to side on this model (the box it fits in, not its volume). [7]
The model has no shape for the cerebellar peduncles itself, so it is not measured here. The medulla oblongata that holds it measures about 33 mm front to back, 41 mm top to bottom and 27 mm side to side on this model (the box it fits in, not its volume). [7]

Sources

Facts describe anatomy and normal function only. The 3D model is the adult male BodyParts3D brain (credits and licence); real brains vary in size and shape, so its measurements describe one model, not anyone’s brain.