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Neurology lab#6
April 12-4-2011
‫بسم هللا الرحمن الرحيم‬
The cerebellum
█ External structure:Consists of
two cerebellar hemisphere united in the
midline by the vermis
█ Internal structure
:
Gray mater consisting in▼
{1}cerebllar cortex
{2} ceremllar nuclei
Dentate nuclei
Fastigial nuclei
Emboliform nucli
Globose nucli
▼White mater
█ Cerebellum structurally divided into
1-ant.lobe
2-post.lobe
3-flocculonodular
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█ note befor:☻ afferen fibers
Toward
cerebellum which mean the
cerebellum receive them
☻Efferent fibber: away from cerebellum
which mean cerebellum project them
☻ always any injure in cerebllum lead
to ipsilateral effect because tract
away and toward
Cerebllum walk ipsilateral or make
2crossing so the net is ipsilatral
☻No direct effect of cerebellum on the
lower motor neurons thus cerebellum
Affect On the body movement via
affecting on the origin of the
descending tract which terminate at
lower motor neurons
█Cerebellum functionally divided
Into:
(1)-vestibulocerebllum:
☻ Floculo-nodular lobe
☻ it receives afferent
fibers from vestibular nuclei of
vestibular nerve in brain stem and
inner ear
☻it project efferent fiber to
vestibular nuclei ln brain stem →
2
-
vestibulospinal tract → motor neurons
of anterior horn
☼☼you notice that vestibular
nuclei
project and receives fibers
from cerebllum
☻Function: involved in eye movements
and maintain balance
☼☼as you know vestibulospinal tract in
the origion is ipsilatral
(2)-spinocerebllum:
☻vermis and intermediate zone
☻it receives afferent fiber{sensory
input}
via spinocerebellar tracts{ant
and post spinocerebllum tracts}
-
☻it project efferent fibers from
-A- vermis to the fastigial nucleus in
cerebllum → vestibular nuclei in brain
stem → vestibulospinal tract → motor
neurons of anterior horn {fastigial
vestibular pathway}
-B- vermis to the fastigial nucleus
→ reticular formation in brain stem →
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reticulospinal tract → motor neurons of
anterior horn{ Fastigeal reticular
pathway}
-C-intermedeat zone to interposed
nuclei{ Globose and emboliform in
cerebllum}then to Contralateral
red nucleus in brain stem →
rubrospinal tract →motor neurons
of anterior horn{ Globoseemboliform-rubral pathway}
☼☼You notice that from the
interposed nuclei to red nuclei
{1crossing}+rubrospinal
tract{1crossing}so 2 crossing
☻Function: play an important role in
control of muscle tone and coordination
of muscle movement on the same side of
the body
(3)- Cerebrocerebellum
☻latral zone
:
☻it receives afferent fibers from
the cerebral cortex via a relay in
pontine
nuclei(corticopontocerebellar
pathway)which mean that these
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fibers come from cortex of
cerebrum then relay in nuclei of
pons then go to cerbllum
☻ It project efferent fibers to
dentate nucleus
→
contralateral thalamus → primary
motor cortex
→ corticospinal
tract → motor neurons of anterior
horn
☼☼You notice that from dentate nucleus
to contralatral
thalamus {1crossing}+corticospinal
tract{1crossing}so 2crossing
☼☼other ex about afferent fiber which
cerebellum receive them in
cerebrocerebellum
◄ corticoreticular cerebellar
pathway{from cerebral cortex to
reticular information in brain steam
then to cerebellum
◄ cortico-olivary cerebellar
pathway[from cerebral cortex to olivary
then to cerebellum}
█ Summary for Cerebellar efferent
fibers:
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Globose-emboliform-rubral pathway☻
Dentothalamic pathway
☻
Fastigial reticular pathway☻
Fastigial vestibular pathway
☻
█ summary for cerebllar afferent
fibers:
☻ Afferent fibers from cerebral
cortex: corticopontocerebellar pathway
☻Afferent fibers from spinal cord:
Anterior and posterior spinocerebellar
tracts
☻Afferent fibers from vestibular nerve
█ Summary for the
function of
cerebllum :-Planning & coordinating the
activities of muscle groups
-Control posture
-Balance & coordination
-Regulation of muscle tone
☼☼ The cerebellum does not initiate
movement, but it contributes to
coordination, precision, and accurate
timing
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☼☼damage to the cerebellum does not
cause paralysis, but instead produces
disorders in fine movement,
equilibrium, posture, and motor
learning.
Signs & symptoms of cerebellar disease█
1) Loss of the ability to coordinate muscular movement
(Ataxia ) { the main cause is cerebellar injure}
2) the inability to judge
on nose test(dysmetria)
position of tip of nose
and when to stop like finger
he can not define the righ
3) the inability to perform rapid alternating movements
spination & pronation (adiadochokinesia)
4) movement tremors (intention tremor)
5) staggering, wide based walking {for balance}
6) tendency toward falling
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7) weak muscles (hypotonia)
8) slurred speech
9) abnormal eye movements (nystagmus)
☼☼Cerebellar injury results in movements that are
slow and uncoordinated. Individuals with cerebellar
lesions tend to sway and stagger when walking
☼☼A lesion in one cerebellar hemisphere gives rise
to signs & symptoms that are limited to the same side
of the body
☼☼A lesion in both cerebellar hemisphere gives rise to
signs & symptoms that are the patient can not walk or
standup{ tendency toward falling }
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Lower +upper
Basal ganglion
neurons nurone
Cerebellum
The main effectors on the body movement
Cerebellar ataxia : have the following if there is
for ex Left cerebellar tumor
-Sways to the right in standing poition
- Steady on the right leg
- Unsteady on the left leg
-ataxic gait
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