Download The Cerebellum

The Cerebellum
Position
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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
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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
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Tonsil of cerebellum
two elevated masses
on inferior surface of
hemispheral portion just
nearby foramen
magnum
Lobes
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Two deep fissures
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Primary fissure
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Uvulonodular fissure
Three lobs
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Flocculonodular lobe
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Anterior
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Posterior lobe
Lobes
Anterior lobe
corpus of
cerebellar
Primary fissure
Posterior lobe
Flocculonodular lobe
Posterolateral fissure
Internal structures
Gray matter
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Cerebellar cortex
Cerebellar nuclei
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Dentate nucleus
Fastigial nucleus
Emboliform nucleus
Globose nucleus
White matter
Internal structures
Cerebellar cortex
Fastigial nucleus
Globose nucleus
Dentate nucleus
medullary center
Emboliform nucleus
Deep Nuclei
1. fastigial
nucleus
2. globose
nucleus
3. emboliform
nucleus
4. dentate
nucleus
Three functional divisions
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Lateral zone
Intermediate zone
Vermis
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Vestibulocerebellum
 Archicerebellum
 Flocculonodular lobe
Spinocerebellum
 Paleocerebellum
 Vermis and intermediate
zone
Cerebrocerebellum
 Neocerebellum
 Lateral zone
Flocculonodular lobe
Cerebellar divisions
Spinocerebellum:
Vermis
Intermediate hem.
Cerebrocerebellum:
Lateral hem.
Spinocerebellum
(Vermis + Intermed. Hem)
Control of limbs
and trunk
Cerebrocerebellum
(Lateral hemisphere)
Planning of movement+
Vestibulo-cerebellum
(Floculo-nodular lobe)
IVth vent
Vermis
Intermediate hem.
Lateral hem.
Control of eye &
head movements
Balance
Floculo-nodular lobe
Connections and function of cerebellum
Vestibulocerebellum
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Connections
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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
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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
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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
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Cerebellar efferent fibers:
Globose-emboliform-rubral pathway
Dentothalamic pathway
Fastigial reticular pathway
Fastigial vestibular pathway
summary
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Cerebellar afferent fibers:
Afferent fibers from cerebral cortex:
corticopontocerebellar pathway.
Afferent fibers from spinal cord: Anterior and
posterior spinocerebellar tracts
Afferent fibers from vestibular nerve
Pyramidal Tract and Associated Circuits
upper motor neuron
UMN
BASAL
GANGLIA
Cerebellum
pyramidal
tract
lower motor neuron
UMN
Cerebellum
Function
 Maintenance of Equilibrium
- balance, posture, eye movement
 Coordination of movement of
walking and posture maintenance
- posture, gait
 Adjustment of Muscle Tone
 Motor Learning – Motor Skills
Balance
Motor Skill
Pablo Casals
Cerebellum
Clinical
Syndromes
1-Ataxia: incoordination of movement
- decomposition of movement
- tremor
- past-pointing
2- dysdiadochokinesia
3-Hypotonia, Nystagmus
4- dysarthria
Posture
Gait – Ataxia
a
d
b
c
Cerebellar
Ataxia
Ataxic gait and
position:
Left cerebellar tumor
a. Sways to the right in
standing position
b. Steady on the
right leg
c. Unsteady on the
left leg
d. ataxic gait