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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 [edit on Wikidata]

The pontocerebellar fibers are the second-order fibers of the corticopontocerebellar tract.^{[citation needed]} They arise from the nuclei pontis as the second leg of the path of the corticopontocerebellar tract (the first part being the corticopontine fibers which synapse in the nuclei pontis), and deecussate (cross-over) in the pons before passing through the middle cerebellar peduncle to reach and terminate in the contralateral posterior lobe of cerebellum (neocerebellum). It is part of a pathway involved in coordination of voluntary movements.^[1]

The middle cerebellar peduncle consists entirely of pontocerebellar fibers; it is the largest pathway of the cerebellum.^[1]

Anatomy[edit]

The fibers are horizontally oriented, forming bundles which pass dorsally through the pons among the nuclei pontis and interweaving with the perpendicularly orietned corticospinal fiber.^[1]

Termination[edit]

The pontocerebellar fibers terminate throughout the cerebellar cortex except the flocculonodular lobe in an arrangement corresponding to the cortical origin of the pathway: efferents of the primary motor cortex project to the vermis and paravermal zone; efferents of the premotor, somatosensory, and association cortex project to the cerebellar hemisphere cortex. Additionally, the fibers also issue collaterals to the dentate nucleus.^[1]

Pathway[edit]

The entire pathway begins and ends in the cerebral cortex, and its entire course is the following:^[1]

(Motor and sensory areas of) cerebral cortex → corticopontine fibers → (ipsilateral) nuclei pontis (synapse) → pontocerebellar fibers (decussation within pons) → 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 of inferior colliculus) → (ipsilateral) (ventral lateral nucleus of) thalamus → (ipsilateral) motor (cerebral) cortex (predominately premotor cortex and primary motor cortex)

Clinical significance[edit]

Damage to the pontocerebellar fibers (or nuclei pontis) will result in contralateral ataxia: 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 motor latral corticospinal tract then decussates once during its descend to control movement of the opposite side of the body.^[1]

References[edit]

^ ^a ^b ^c ^d ^e ^f Patestas, Maria A.; Gartner, Leslie P. (2016). A Textbook of Neuroanatomy (2nd ed.). Hoboken, New Jersey: Wiley-Blackwell. pp. 109–110, 113, 116, 292, 295–296. ISBN 978-1-118-67746-9.

External links[edit]

Anatomy of the cerebellum

Surface

Lobes	Anterior lobe Posterior lobe Horizontal fissure Flocculonodular lobe Flocculus Nodule Primary fissure
Medial/lateral	Vermis: anterior Central lobule Culmen Lingula posterior Folium Tuber Uvula Vallecula of cerebellum Hemisphere: anterior Alar central lobule posterior Biventer lobule Cerebellar tonsil

Grey matter

Deep cerebellar nuclei	Dentate interposed Emboliform Globose Fastigial
Cerebellar cortex	Molecular layer Stellate cell Basket cell Purkinje cell layer Purkinje cell Bergmann glia cell = Golgi epithelial cell Fañanas cell Granule cell layer Golgi cell Granule cell Unipolar brush cell Fibers: Mossy fibers Climbing fiber Parallel fiber

White matter

Internal	Arbor vitae
Peduncles	Inferior (medulla): Dorsal spinocerebellar tract Olivocerebellar tract Cuneocerebellar tract Juxtarestiform body (Vestibulocerebellar tract) Trigeminocerebellar fibers Middle (pons): Pontocerebellar fibers Superior (midbrain): Ventral spinocerebellar tract Dentatothalamic tract

Anatomy of the pons

Dorsal/
(tegmentum)

Surface

White: Sensory

White: Motor

Grey: Cranial nuclei

afferent:	GSA Trigeminal Principal Spinal Cochlear nucleus Dorsal Anterior Vestibular nuclei Superior
efferent:	SVE: Trigeminal motor nucleus Facial motor nucleus GSE: Abducens nucleus GVE: Superior salivary nucleus Inferior salivary nucleus

Grey: Other nuclei

Ventral/
(base)

Grey	Pontine nuclei
White: Motor/descending	Corticospinal tract Corticobulbar tract Corticopontine fibers MCP Pontocerebellar fibers
Surface	Basilar sulcus

Other grey: Raphe/
reticular

Brain and spinal cord: neural tracts and fasciculi

Sensory

DCML

1°:	Pacinian corpuscle/Meissner's corpuscle → Posterior column (Gracile fasciculus/Cuneate fasciculus) → Gracile nucleus/Cuneate nucleus
2°:	→ sensory decussation/arcuate fibers (Posterior external arcuate fibers, Internal arcuate fibers) → Medial lemniscus/Trigeminal lemniscus → Thalamus (VPL, VPM)
3°:	→ Posterior limb of internal capsule → Postcentral gyrus

Anterolateral/
pain

Fast/lateral	1° (Free nerve ending → A delta fiber) → 2° (Anterior white commissure → Lateral and Anterior Spinothalamic tract → Spinal lemniscus → VPL of Thalamus) → 3° (Postcentral gyrus) → 4° (Posterior parietal cortex) 2° (Spinomesencephalic tract → Superior colliculus of Midbrain tectum)
Slow/medial	1° (Group C nerve fiber → Spinoreticular tract → Reticular formation) → 2° (MD of Thalamus) → 3° (Cingulate cortex)

Motor

Pyramidal

flexion: Primary motor cortex → Posterior limb of internal capsule → Decussation of pyramids → Corticospinal tract (Lateral, Anterior) → Neuromuscular junction

Extrapyramidal

flexion:	Primary motor cortex → Genu of internal capsule → Corticobulbar tract → Facial motor nucleus → Facial muscles
flexion:	Red nucleus → Rubrospinal tract
extension:	Vestibulocerebellum → Vestibular nuclei → Vestibulospinal tract
extension:	Vestibulocerebellum → Reticular formation → Reticulospinal tract
Midbrain tectum → Tectospinal tract → muscles of neck

Basal ganglia

direct:	1° (Motor cortex → Striatum) → 2° (GPi) → 3° (Lenticular fasciculus/Ansa lenticularis → Thalamic fasciculus → VL of Thalamus) → 4° (Thalamocortical radiations → Supplementary motor area) → 5° (Motor cortex)
indirect:	1° (Motor cortex → Striatum) → 2° (GPe) → 3° (Subthalamic fasciculus → Subthalamic nucleus) → 4° (Subthalamic fasciculus → GPi) → 5° (Lenticular fasciculus/Ansa lenticularis → Thalamic fasciculus → VL of Thalamus) → 6° (Thalamocortical radiations → Supplementary motor area) → 7° (Motor cortex)
nigrostriatal pathway:	Pars compacta → Striatum

Cerebellar

Afferent

Vestibular nuclei → Vestibulocerebellar tract → ICP → Cerebellum → Granule cell

Pontine nuclei → Pontocerebellar fibers → MCP → Deep cerebellar nuclei → Granule cell

Inferior olivary nucleus → Olivocerebellar tract → ICP → Hemisphere → Purkinje cell → Deep cerebellar nuclei

Efferent

Dentate nucleus in Lateral hemisphere/pontocerebellum → SCP → Dentatothalamic tract → Thalamus (VL) → Motor cortex

Interposed nucleus in Intermediate hemisphere/spinocerebellum → SCP → Reticular formation, or → Cerebellothalamic tract → Red nucleus → Thalamus (VL) → Motor cortex

Fastigial nucleus in Flocculonodular lobe/vestibulocerebellum → Vestibulocerebellar tract → Vestibular nuclei

Bidirectional:
Spinocerebellar

Unconscious proprioception	lower limb → 1° (muscle spindles → DRG) → 2° (Posterior thoracic nucleus → Dorsal/posterior spinocerebellar tract → ICP → Cerebellar vermis) upper limb → 1° (muscle spindles → DRG) → 2° (Accessory cuneate nucleus → Cuneocerebellar tract → ICP → Anterior lobe of cerebellum)
Reflex arc	lower limb → 1° (Golgi tendon organ) → 2° (Ventral/anterior spinocerebellar tract→ SCP → Cerebellar vermis) upper limb → 1° (Golgi tendon organ) → 2° (Rostral spinocerebellar tract → ICP → Cerebellum)

Terminologia Anatomica

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