the cerebellum-8.pdf

8/17/2019 The Cerebellum-8.pdf

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The Cerebellum


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Objectives:

• Name the major lobes of the cerebellumand give the function of each lobe.

• Describe the division of the cerebelluminto a midline vermis and lateral cerebellarhemispheres.

• Describe the histology of the cerebellar

cortex.• Name the deep cerebellar nuclei and theirgeneral connections.


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Objectives:• Name the types of afferent fibers to thecerebellar cortex and identify their source.• Name the efferent fibers from the

cerebellar cortex.• Trace the various circuitries within the

cerebellar cortex.• Name the cerebellar peduncles and the

fiber tracts (afferent and efferent) thatconstitute them.

• Describe the cerebellar connections

of the vestibular system.


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Cerebellum:Vermis

Cerebellar hemispheres

Sulci/fissures


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Inferior(restiform body)

medulla

Cerebellarpeduncles:

Superior(brachiumconjunctivum)

midbrain

Middle(brachiumpontis) pons

* juxtarestiform body- medial part


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Cerebellum:

• Coordination of voluntary muscle activity• Equilibrium

• Muscle tonus

Each cerebellar hemisphere controls muscular

movements on the same side of the body.

ESM


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The cerebellum has no direct PW to the LMN’s exerts its control via the cerebral cortex and

the brainstem… Does NOTinitiatemovement

X- Coordination of eye andlimb mov’ts. slow,

tremulous, and

uncoordinated


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The cerebellum has no direct PW to the LMN’s exerts its control via the cerebral cortex and

the brainstem…

X- Movement

X- Muscle tone and posture hyper- or hypotonic; cannotstand or walk w/o swaying


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3 Main Lobes: (transverse divisions)

1.) Paleocerebellum

- input: spinocerebellar and trigeminocerebellar PW’s

- stance and gait


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2.) Neo cerebellum-input: cerebral

cortex

- speech andcoordinatedmovement

- mayherniate


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3.) Archicerebellum- flocculonodular lobe (oldest)

- input: vestibular nuclei

- equilibrium (balance, posture, eye movements)

/nodulus Posterolateralfissure


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Cortex…


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Whitematter


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Junqueira’s Basic Histology Text and Atlas 12 th ed. Anthony L. Mescher,The McGraw-Hill Companies, Inc.


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foliumArborvitae


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Intracerebellar

nucleiLarge, multipolarneuronsSimple branchjng

dendrites

Axons


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Intracerebellarnuclei

Interposednuclei


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Functional Areas of theCerebellar Cortex:

(sagittal divisions)

v

er mis

int

zone

later al

zon

e

Vermal flocculonodular z.:

Flocculonodular lobe and(posterior) vermis

Vermis/


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v

er mis

int

zone

later al

zon

e

- long axis of the body

- cortex of flocculonodularlobe and vermis fastigial nuclei

vestibular nuclei spinal

cord

Vermal flocculonodular z.:Vermis/


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v

er mis

int

zone

later al

zon

e- control of posture,muscle tone, locomotion,equilibrium

Vermal flocculonodular z.:Vermis/

Damage: ataxia


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v

er mis

int

zone

later al

zon

e

Paravermal/

Intermediate Zone:

- anterior lobe and(anterior) vermis nucleus interpositus

red nucleus,contralateral cross

spinal cord

- limbs


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v

er mis

int

zone

later al

zon

e

Paravermal/

Intermediate Zone:

spinal cord

- limbs

Disease:Wide-based stance

Walking: stagger


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(sagittal divisions)v

er mis

int

zone

later

al

zon

e

Lateral Zone:

- dentate nuclei thalamus motorcortex pontine nuclei,spinal cord (ant. horn

cells)


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er mis

int

zone

later

al

zon

e- coordination ofipsilateral somatic motor

activity

- planning ofmovements

- assessment oferrors

Lateral Zone:


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er mis

int

zone

later

al

zon

e

Lateral Zone:Lesions: cerebellarincoordination (asynergia)

Dysmetria

Past-pointing

Tremor

Dysdiadochokinesis-inability to perform regular/rapidly alternating movements

Rebound phenomenon


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Cortex: Gray Matter

3 Layers


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Basket celldendritesand axons

Molecular Layer:

Stellate cell


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Junqueira’s Basic Histology Text and

Atlas 12th

ed. Anthony L. Mescher,The McGraw-Hill Companies, Inc.


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Purkinje Cell Layer:

- Golgi Type I

- flask-shaped

- one layer


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Junqueira’s Basic Histology Text and

Atlas 12 th ed. Anthony L. Mescher,The McGraw-Hill Companies, Inc.


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Granular Layer:

Granule cell- smallest neuron

Golgi type II cell

Glomeruli


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Granular Layer:

Granule cell

Golgi cell

A

D


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Granular Layer:

Granule cell

Golgi type II cell

Glomeruli or

cerebellar islands-mossy fiber rosette(center)


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Climbing and MossyFibers:

- lines of input- excitatory to

Purkinje cells


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Climbing Fibers:

- ends:olivocerebellartract

- synapse withcells: (collaterals)Purkinje

Golgi type IIbasketstellate


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- ends of all othercerebellar tracts

- diffuse effect

Mossy Fibers:

Other cells:

Basket

Stellate

Golgi

Inhibitoryinterneurons

Purkinje cell-

functional unit


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(-)

(+)(-)

(-)

(-)

(+)- Excitatory

(-)- Inhibitory

Climbing fiber Glutamate/ aspartate

GABA

GABA

GABA

Inferiorolive

Mossy fiber Glutamate, ACh

GABA (+)(-)

( - )

(-)

(+)(+)

(-)

Cerebellar Cortex Circuitry:


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(+)

(+)- Excitatory

(-)- Inhibitory

Climbing fiber Glutamate/ aspartate

Inferiorolive

Mossy fiber Glutamate, ACh

(+)

(+)(+)



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(-)

(-)

(-)

(-)

(+)- Excitatory

(-)- Inhibitory

GABA

GABA

GABA

Inferiorolive

GABA(-)

( - )

(-)(-)



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(-)

(+)(-)

(-)

(-) (+)

(-)

( - )

(-)

(+)(+)Cerebellum:

Monitors and triggersnew/modifies movements…


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(-)

(+)(-)

(-)

(-) (+)

(-)

( - )

(-)

(+)(+)

Ensure speed andaccuracy of movements


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White Matter: 3 Groups of Fibers

1. Intrinsic2. Afferent

cerebellar

cortex

- Inf. and middle

cer. peduncles

3. Efferent…


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White Matter: 3 Groups of Fibers

3. Efferent

- Purkinje cell axons

intracerebellarnuclei

(a few bypass it)


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Cerebellar Afferent Fibers:

• From the cerebral cortexPathways/tracts:- corticopontocerebellar

- cerebro-olivocerebellar- cerebroreticulocerebellar

Important in the control ofvoluntary movement;initiation of movement


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• From the spinal cord- anterior spinocerebellar- posterior spinocerebellar

- cuneocerebellar

- Information is sent fromthe somatosensory

receptors


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From the vestibular nerve flocculonodular lobe

Receive information from

the inner ear:motion

position

• Vestibulocerebellar:


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Cerebro(cortico)-olivocerebellar PW

climbing

fibers

Information:

Motor area

Inf. olivarynucleus


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CerebroreticulocerebellarPW

Cerebellar AfferentFibers:

Information:Motor areas

paravermalregions

reticularformation

pons andmedulla


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Anterior Spinocerebellar tract (majority of fibers)

CerebellarAfferent Fibers:

- conveymuscle-jointinformation

paravermalregions

nucleusdorsalis

Muscle spindles,tendon organs, and

joint receptors of theupper and lowerlimbs; skin and

superficial fascia

- all segments

of spinal cord

ff


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Posterior Spinocerebellartract

- convey muscle-joint

information

- trunk and lower limbs

paravermalregions

nucleusdorsalis

b ll ff


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CuneocerebellarTract

nucleus cuneatus- convey muscle-joint

information- UL and upper part,

thorax

C b ll Aff


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From the vestibularnerve

All afferent fibersterminate in theflocculonodular lobe

vestibular nuclei

T bl 6 1 Th Aff t C b ll P th


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Table 6-1 The Afferent Cerebellar Pathways:

Pathway: Function: Origin: Destination:Corticoponto-cerebellar

Conveys control fromcerebral cortex

Cerebral lobes Via pontine nuclei andmossy fibers tocerebellar cortex

Cerebro-olivocerebellar

Via inf. olivary nucleiand climbing fibers tocerebellar cortex

Cerebroreticulo-cerebellar

Sensorimotorareas

Via reticular formation

Ant. and Post.spinocerebellar

Conveys informationfrom muscles and

joints

Muscle spindles,tendon organs,and jointreceptors

Via mossy fibers tocerebellar cortex

Cuneo-cerebellar

Conveys info. fromms. and jts. of UL

Vestibular nerve Conveys informationof head position andmovement

Utricle, saccule,and semicircularcanals

Via mossy fibers tocortex offlocculonodular lobe

Other afferents Conveys informationfrom midbrain

Red nucleus,tectum

Cerebellar cortex

C b ll


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Entireoutput

most axons

CerebellarEfferent Fibers:

Red nucleus

Thalamus

Vestibularcomplex

Reticularformation

C b ll


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Entireoutput

most axons

Lateral

vestibularnucleus

CerebellarEfferent Fibers:

Red nucleus

Thalamus

Vestibularcomplex

Reticularformation


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Cerebellar Efferent Fibers:

• Globose-Emboliform-Rubral Pathway• Dentothalamic PW• Fastigial Vestibular PW

• Fastigial Reticular PW


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* Decussation ofthe superiorcerebellar

peduncle

Globose-Emboliform-Rubral PW

Influencesipsilateral motor

activity

rubrospinal tract

1 motor areacerebral cortex


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VL nucleusthalamus

cerebral cortex

Influencesipsilateral motor

activity

DentothalamicPW

corticospinal fibers

decussation of pyramid


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lateral vestibular nucleus Fastigialvestibular PW

Influencesipsilateral extensor

muscle tone

vestibulospinal tract


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FastigialReticular PW

reticulospinal tract

reticular formation

Influences

ipsilateral muscletone

Table 6-2 The Efferent Cerebellar Pathways:


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Pathway: Function: Origin: Destination:

Globose-emboliform-

rubral

Influencesipsilateral

motor activity

Globoseemboliform

nuclei

To CL red nucleus, then viacrossed rubrospinal tract to

ipsilateral motor neurons inspinal cord

Dentothalamic Influencesipsilateralmotor activity

Dentatenucleus

To CL VL nucleus of thalamus,then to CL motor cerebralcortex; corticospinal tractcrosses midline and controlsipsilateral motor neurons inspinal cord

Fastigialvestibular

Influencesipsilateralextensormuscle tone

Fastigialnucleus

Mainly to ipsilateral and to CLlateral vestibular nuclei;vestibulospinal tract to ipsilateralmotor neurons in spinal cord

Fastigialreticular

Influencesipsilateralmuscle tone

Fastigialnucleus

To neurons of reticularformation; reticulospinal tract toipsilateral motor neurons tospinal cord


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Cortico pontomotor cortex


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Cortico-ponto-cerebello-dentato-

thalamo-corticalPW

Corticopontine tracts

pontine nucleimiddle cerebellarpeduncle

Purkinje axon

dentate nucleus

dentatothalamicfibers (crossed)

dentatothalamic

fibers (uncrossed)

thalamus

VL

Doubledecussation:

- pontine level

- superior cerebellarpeduncle

decussation of sup.cerebellar peduncle

pontocerebellar fibers(crossed)

cortex

Cortico-ponto-motor cortex


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Cortico-ponto-cerebello-dentato-

thalamo-corticalPW

Corticopontine tracts

pontine nucleimiddle cerebellarpeduncle

Purkinje axon

dentate nucleus

dentatothalamicfibers (crossed)

dentatothalamic

fibers (uncrossed)

thalamus

VL

From motorcortex loop

influencesdescending motor

PW’s

decussation of sup.cerebellar peduncle

Vestibulo


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Vestibulo-archicerebellar

Loop

vestibular n.

vestibular nuclei

vestibulocerebellar projections:direct and indirect

flocculonodularlobe

fastigia l nucleus

Influences tospinal motoractivity occurthrough the

vestibulospinaltracts

medial vestibulospinal tracts

(and reticular nuclei)

juxtarestiform body


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Brainstem nuclei-cerebellar Loop

reticulocerebellartract

olivocerebellartract

inferior olivary nucleus

reticularformation


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Cerebellar Cortical Circuitry:


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Origin:

cerebral cortex

muscles,tendons, and

jointsvestibular nerve

(few)

(most)

Cerebellar Cortical Circuitry:In summary…


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(few)

(most)

Inhibitoryinfluence

lateral vestibular

nucleus


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Cerebellum-NO DIRECT

neuronalconnections with

LMN’s

- INDIRECT


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Cerebellum- coordinator of precise movements

- bring about the necessary adjustments

- influence activity of LMN’s

(motor area)


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Cerebellum- send back information

inhibit agonist muscles; stimulate antagonist ms.

limits voluntary movement

(motor area)


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Objectives:

• Name the major lobes of the cerebellumand give the function of each lobe.

• Describe the division of the cerebellum

into a midline vermis and lateral cerebellarhemispheres.• Describe the histology of the cerebellar

cortex.• Name the deep cerebellar nuclei and their

general connections.


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Thank you


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Manter and Gatz’ Essentials of ClinicalNeuroanatomy and Neurophysiology 10 th ed. Sid Gilman, MD, FRCP, Sarah Winans Newman, PhD; F.A. Davis PublishersPhiladelphia

Clincal Neuroanatomy 7 th ed., 2010

Richard S. Snell

Wolters Kluwer/Lippincott Williams and

Wilkins

Lansang Notes: Modules in Anatomy 4 th ed. Esperanza N. Carague-Lansang, MD, Ma. Cristina S. Elma, MD, Luis Emmanuel O.Esguerra, MD

Thank you…

the cerebellum-8.pdf

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