The Cerebellum

Position

Lies above and behind the medulla and pons and occupies posterior cranial fossa

Its surface is high convoluted, forming folds or folia, being oriented transversely

Cerebellum

External features

Consists of two cerebellar hemisphere united in the midline by the vermis

External features

Three peduncles Inferior cerebellar

peduncle － connect with medulla and with spinal cord, contain both afferent and efferent fibers

Middle cerebellar peduncle － connect with pons, contain afferent fibers

Superior cerebellar peduncle － connect with midbrain, contain mostly efferent fibers

External features

Tonsil of cerebellum two elevated masses on inferior surface of hemispheral portion just nearby foramen magnum

Lobes

Two deep fissures

Primary fissure

Uvulonodular fissure

Three lobs

Flocculonodular lobe

Anterior

Posterior lobe

Lobes

Primary fissure

Posterolateral fissureFlocculonodular lobe

Anterior lobe

Posterior lobe

corpus of cerebellar

Internal structures Gray matter Cerebellar cortex Cerebellar nuclei

Dentate nucleus Fastigial nucleus Emboliform nucleus Globose nucleus

White matter

Internal structures

Cerebellar cortex

Dentate nucleus

Fastigial nucleus

Globose nucleus

Emboliform nucleus

medullary center

1. fastigial 1. fastigial

nucleusnucleus

2. globose 2. globose

nucleusnucleus

3. emboliform 3. emboliform

nucleusnucleus

4. dentate 4. dentate

nucleusnucleus

Deep NucleiDeep Nuclei

Three functional divisions Vestibulocerebellum

Archicerebellum Flocculonodular lobe

Spinocerebellum Paleocerebellum Vermis and intermediate

zone Cerebrocerebellum

Neocerebellum Lateral zone

Flocculonodular lobe

Verm

is In

termed

iate zo

ne

Lateral

zon

e

IVth vent VermisIntermediate hem.

Spinocerebellum: Vermis Intermediate hem.Spinocerebellum

(Vermis + Intermed. Hem)

Control of limbs and trunk

Lateral hem.

Cerebrocerebellum: Lateral hem.

Cerebrocerebellum(Lateral hemisphere)

Planning of movement+

Floculo-nodular lobe

Vestibulo-cerebellum(Floculo-nodular lobe)

Control of eye & head movementsBalance

Cerebellar divisions

Connections and function of cerebellum

Vestibulocerebellum Connections

Afferents: receive input from vestibular nuclei and inner ear.

Efferents: projects to the vestibular nucleus → vestibulospinal → motor neurons of anterior horn

Function: involved in eye movements and maintain balance

Connections and function of cerebellum

Spinocerebellum Connnection

Afferents: receive somatic sensory information via spinocerebellar tracts

Efferents: Fastigeal reticular and fastigial vestibular pathways:

Vermis projects to the fastigial nucleus → vestibular nuclei and reticular formation → vestibulospinal tract and reticulospinal tract → motor neurons of anterior horn

Intermediate zone projects to the interposed nuclei Globose- emboliform-rubral pathway: Contralateral red nucleus →

rubrospinal tract →motor neurons of anterior horn

Function: play an important role in control of muscle tone and coordination of muscle movement on the same side of the body

Connections and function of cerebellum

Cerebrocerebellum Connection

Afferents: receives input from the cerebral cortex via a relay in pontine nuclei(corticopontocerebellar pathway)

Efferents: (dentothalamic pathway):

dentate nucleus → contralateral thalamus → primary motor cortex → corticospinal tract → motor neurons of anterior horn

Function: participates in planning movements

summary

Cerebellar efferent fibers:

1. Globose-emboliform-rubral pathway

2. Dentothalamic pathway

3. Fastigial reticular pathway

4. Fastigial vestibular pathway

summary

Cerebellar afferent fibers:

1. Afferent fibers from cerebral cortex: corticopontocerebellar pathway.

2. Afferent fibers from spinal cord: Anterior and posterior spinocerebellar tracts

3. Afferent fibers from vestibular nerve

upper motor neuronupper motor neuron

UMNUMN

upper motor neuronupper motor neuron

UMNUMN

BASALBASALGANGLIAGANGLIABASALBASAL

GANGLIAGANGLIA

Pyramidal Tract and Associated CircuitsPyramidal Tract and Associated CircuitsPyramidal Tract and Associated CircuitsPyramidal Tract and Associated Circuits

lower motor neuronlower motor neuron

UMNUMN

lower motor neuronlower motor neuron

UMNUMN

pyramidal tractpyramidal tract

CerebellumCerebellumCerebellumCerebellum

CerebellumCerebellum FunctionFunction

CerebellumCerebellum FunctionFunction

Maintenance of EquilibriumMaintenance of Equilibrium - balance, posture, eye movement - balance, posture, eye movement

Coordination of movement ofCoordination of movement of walking and posture maintenancewalking and posture maintenance - posture, gait - posture, gait

Adjustment of Muscle ToneAdjustment of Muscle Tone

Motor Learning – Motor SkillsMotor Learning – Motor Skills

BalanceBalance

Motor Skill Motor Skill

Pablo CasalsPablo CasalsPablo CasalsPablo Casals

CerebellumCerebellum Clinical Clinical SyndromesSyndromes

CerebellumCerebellum Clinical Clinical SyndromesSyndromes

1-Ataxia1-Ataxia: incoordination of movement: incoordination of movement - decomposition of movement- decomposition of movement - tremor - tremor - past-pointing- past-pointing2- dysdiadochokinesia2- dysdiadochokinesia3-Hypotonia3-Hypotonia, , NystagmusNystagmus4- dysarthria4- dysarthria

PosturePostureGait – AtaxiaGait – Ataxia

Cerebellar Cerebellar AtaxiaAtaxia

Ataxic gait and Ataxic gait and position: position: Left cerebellar tumorLeft cerebellar tumor

a. Sways to the right ina. Sways to the right in standing positionstanding position

b. Steady on the b. Steady on the right legright leg

c. Unsteady on the c. Unsteady on the left legleft leg

d. ataxic gaitd. ataxic gait

a b c

d