Cerebellum
Dr. Safaa
Objectives
• Identify the major lobes and regions of cerebellum.
• Summarize the structure of the cerebellar cortex
• Identify the deep cerebellar nuclei and their
connections.
• List the afferent and efferent connections of the
cerebellum and their arrangement in cerebellar
peduncles.
• Describe the major functions of the cerebellum and
how each side of the cerebellum controls the
ipsilateral side of the body.
• Explain the effects of lesions of cerebellum and motor
disorder associated with cerebellar lesions.
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Gross Appearance of the Cerebellum
The cerebellum is situated in posterior cranial fossa
Covered superiorly by tentorium cerebelli.
Lies posterior to the fourth ventricle, the pons, and
the medulla oblongata.
It consists of two cerebellar hemispheres joined
vermis.
The cerebellum is connected to the posterior aspect
of the brainstem by:
Superior cerebellar peduncles (midbrain).
Middle cerebellar peduncles (pons).
Inferior cerebellar peduncles (medulla oblongata).
Cerebellum
• The cerebellum is
divided into three main
lobes:
• Anterior lobe which is
separated from the
middle lobe primary
fissure.
• Middle (posterior) lobe
which is situated
between the primary and
uvulonodular fissures.
• Flocculonodular lobe.
which is situated
posterior to the
uvulonodular fissure
A deep horizontal fissure
separates the superior
from the inferior
surfaces.
• Structure of the
Cerebellum
• The cerebellum is
composed of:
• Outer cortex of gray
matter.
• Inner white matter.
• Three masses of gray
matter (intracerebellar
nuclei) are embedded in
the white matter.
• The cerebellar cortex is formed
of folds called folia.
• Each fold or folium contains a
core of white matter covered
superficially by gray matter.
• A section made through the
cerebellum parallel with the
median plane has a branched
appearance, called the arbor
vitae.
• The gray matter of the cortex
may be divided into three
layers:
• (1) Molecular layer (stellate &
basket cells).
• (2) Purkinje cell layer (Purkinje
cells) .
• (3) Granular layer (granular &
golgi cells).
Intracerebellar Nuclei:
1.Dentate: The largest of the
cerebellar nuclei. It has the
shape of a crumpled bag
2. Emboliform:Is ovoid
3. Globose: consists of one or
more rounded cell groups
4. Fastigial:Lies near the midline
in the vermis.
• Afferents to these nuclei
from:
• Inhibitory from Purkinje cells.
• Excitatory from climbing and
mossy fibers.
• Efferents from these nuclei
form the cerebellar outflow
in the superior and inferior
cerebellar peduncles.
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White Matter:
The white matter is made up of three groups of fibers:
(1) Intrinsic.
(2) Afferent.
(3) Efferent.
Afferent fibers (mossy & climbing
fibers):
1. From cerebral cortex(Conveys
control from cerebral cortex) :
• Corticopontocerebellar through
pontine nuclei in middle
peduncle & terminates as mossy
fibers to cerebellar cortex.
• Cerebroreticulocerebellar
through reticular formation in
inferior and middle peduncles&
terminates as mossy fibers to
cerebellar cortex.
• Cerebro-olivocerebellar through
inferior olivary nuclei in inferior
peduncle & terminates as
climbing fibers to cerebellar
cortex.
2. From spinal cord (conveys
information from muscles
and joints):
• Anterior spinocerebellar
from nucleus dorsalis
(Clarke's column) majority
crossing and enter
cerebellum through
superior peduncle &
terminates as mossy fibers
to cerebellar cortex.
• Posterior spinocerebellar
from nucleus dorsalis
(Clarke's column) NOT
crossing and enter
cerebellum through
inferior peduncle &
terminates as mossy fibers
to cerebellar cortex.
3. Cuneocerebellar (Conveys
information from muscles and
joints of upper limb) originate
in nucleus cuneatus of medulla
oblongata NOT crossing and
enter cerebellum through
inferior peduncle& terminates
as mossy fibers to cerebellar
cortex.
4. Vestibular nerve (conveys
information of head position
and movement) originate in
inner ear NOT crossing and
enter cerebellum through
inferior peduncle& terminates
as mossy fibers to
flocculonodular lobe.
5. In addition, cerebellum receives
small bundles of afferent fibers
from red nucleus & tectum.
• Efferent fibers (to red
nucleus, thalamus,
vestibular complex, and
reticular formation) :
• Purkinje cell axons synapse
with all cerebellar nuclei
(fastigial, globose,
emboliform, and dentate).
• From dentate, emboliform,
and globose nuclei through
the superior cerebellar
peduncle.
• From fastigial nucleus
leave through the inferior
cerebellar peduncle.
• Each cerebellar hemisphere influences
the voluntary muscle tone on the same
side of the body (ipsilateral).
• The cerebellum has no direct neuronal
connections with the lower motor
neurons but exerts its influence
indirectly through the cerebral cortex
and brainstem.