| Pontocerebellar fibers | |
|---|---|
 Scheme showing the connections of the several parts of the brain. | |
| Details | |
| Identifiers | |
| Latin | fibrae pontocerebellares |
| NeuroNames | 1345 |
| TA98 | A14.1.05.110 |
| TA2 | 5849 |
| FMA | 75215 |
| Anatomical terms of neuroanatomy | |
Thepontocerebellar fibers are thesecond-order neuron fibers of the corticopontocerebellar tracts that cross to the other side of thepons and run within themiddle cerebellar peduncles, from thepons to the contralateralcerebellum.[1]They arise from thepontine nuclei as the second part of the corticopontocerebellar tract (the first part being thecorticopontine fibers which synapse in the pontine nuclei), anddecussate (cross-over) in the pons before passing through themiddle cerebellar peduncles to reach and terminate in the contralateralposterior lobe of the cerebellum (neocerebellum). It is part of a pathway involved in the coordination of voluntary movements.[2]
The middle cerebellar peduncle consists entirely of pontocerebellar fibers and is the largest pathway of the cerebellum.[2]
The fibers are horizontally oriented, forming bundles which pass dorsally through the pons among the pontine nuclei and interweave with the perpendicularly orientedcorticospinal fibers.[2]
The pontocerebellar fibers terminate throughout the cerebellar cortex except theflocculonodular lobe in an arrangement corresponding to the cortical origin of the pathway: efferents of theprimary motor cortex project to thevermis and paravermal zone; efferents of thepremotor,somatosensory, andassociation cortex project to thecerebellar hemisphere cortex. Additionally, the fibers also issue collaterals to thedentate nucleus.[2]
The entire pathway begins and ends in the cerebral cortex, and its entire course is the following:[2]
(Motor and sensory areas of)cerebral cortex →corticopontine fibers → (ipsilateral)nuclei pontis (synapse) → pontocerebellar fibers (decussation withinpons) →middle cerebellar peduncle → (contralateral) (cerebellar cortex and (collaterals)dentate nucleus of)posterior lobe of cerebellum (synapse) →cerebellothalamic tract →superior cerebellar peduncle →mesencephalon (midbrain) (decussation of tract at level ofinferior colliculus) → (ipsilateral) (ventral lateral nucleus of)thalamus → (ipsilateral)motor (cerebral) cortex (predominatelypremotor cortex andprimary motor cortex)
Damage to the pontocerebellar fibers (or pontine nuclei) will result in contralateralataxia: due to the double decussation of the pathway along its entire course, it terminates in the motor cortex of the same cerebral hemisphere in which it began; the motorlateral corticospinal tract then decussates once during its descent to control movement of the opposite side of the body.[2]
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