The Cerebellum

Patient with Cerebellar Problem

Objectives:

Explain the clinical manifestations of cerebellar dysfunction based on the:

a. Structure/s affectedb.Cerebellar cortex circuitry affectedc. Pathway/s involved

Cerebellum:

Vermis

Cerebellar hemispheres

Sulci/fissures

Cerebellar Peduncles & Connections

• Superior (brachium conjunctivum) midbrain

• Middle (brachium pontis) pons

• Inferior (restiform body) medulla

* juxtarestiform body- medial part

Cerebellum:• Coordination of voluntary muscle activity

• Equilibrium

• Muscle tonus

Each cerebellar hemisphere controls muscular movements on the same side of the body.

ESM

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

Does NOT initiate movement

X- Coordination of eye and limb mov’ts. slow,

tremulous, and uncoordinated

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; cannot stand

or walk w/o swaying

3 Main Lobes: (transverse divisions)

1.) Paleocerebellum/Anterior lobe

- input: spinocerebellar and trigeminocerebellar PW’s

- stance and gait

2.) Neocerebellum/Middle lobe/Posterior Lobe

-input: cerebral cortex

- speech and coordinated movement

3.) Archicerebellum- flocculonodular lobe (oldest)

- input: vestibular nuclei

- equilibrium (balance, posture, eye movements)

/nodulus Posterolateral fissure

Lobes of the Cerebellum

Lobes of Cerebellum: Function

Cortex…

White matter

Folium & Arbor Vitae

Junqueira’s Basic Histology Text and Atlas 12th ed. Anthony L. Mescher, The

McGraw-Hill Companies, Inc.

Intracerebellar nuclei

Interposed nuclei

Cerebellar Cortex:Cell Layers

Cortex: Gray Matter

3 Layers

Basket celldendrites and axons

Molecular Layer:

Stellate cell

Cerebellar Cortex: Layers

Purkinje Cell Layer:

- Golgi Type I

- flask-shaped

- one layer

Purkinje Cell Layer

Purkinje Cell Layer:

Junqueira’s Basic Histology Text and Atlas 12th ed. Anthony L. Mescher, The

McGraw-Hill Companies, Inc.

Purkinje Cell Layer:

Myelin sheath

Granular Layer:

Granule cell

Golgi type II cell

Glomeruli or cerebellar islands- mossy fiber rosette (center)

Granular Layer

Cerebellar Circuitry

Cerebellar Circuitry

Cerebellar Circuitry

SummarySpinal cord, pontine nuclei, Inferior OliveVestibular nuclei & ganglia, Trigeminal nuclei, reticular formationNuclei & Deep cerebellar nuclei

Mossy Climbing

Granule Cell Layer Molecular Layer/Dendrites of Purkinje Cells

Efferent: Purkinje cells

(+)

glutamate

(+)- Excitatory

(-)- Inhibitory

Climbing fiber Glutamate/ aspartate

Inferior olive

Mossy fiber Glutamate, ACh

(+)

(+)

(+)(+)

Cerebellar Cortex Circuitry:

(-)

(-)

(-)

(-)

(+)- Excitatory

(-)- Inhibitory

GABA

GABA

GABA

Inferior olive

GABA(-)

(-)

(-)(-)

Cerebellar Cortex Circuitry:

(-)

(+)(-)

(-)

(-)

glutamate

(+)- Excitatory

(-)- Inhibitory

Climbing fiber Glutamate/ aspartate

GABA

GABA

GABA

Inferior olive

Mossy fiber Glutamate, ACh

GABA (+)

(+)

(-)

(-)

(-)

(+)(+)

(-)

Cerebellar Cortex Circuitry:

Cerebral Peduncles:Afferent & Efferent Fibers

Peduncle Afferent Tracts Efferent Tracts

Superior -Anterior spinocerebellar-Trigeminocerebellar (some)

-Dentatorubral-Dentatothalamic-Dentatoreticular

Middle -Pontocerebellar

Inferior -Posterior spinocerebellar-Cuneocerebellar-Reticulocerebellar-Olivocerebellar-Trigeminocerebellar (some)-Vestibulocerebellar

- Fastigiobulbar

Connections of the Cerebellum

Cerebellar Afferent Fibers:• From the cerebral cortex

Pathways/tracts:- corticopontocerebellar- cerebro-olivocerebellar- cerebroreticulocerebellar

Important in the control of voluntary movement;

initiation of movement

Cerebellar Afferent Fibers:

Corticopontocerebellar PW

Information from:

1° motor and sensory areas and associative areas

1° visual cortex

Pontine nuclei

Cerebellar Afferent Fibers:

Cerebro(cortico)-olivocerebellar PW

climbing fibers

Information:

Motor area

Inf. olivary nucleus

Cerebroreticulocerebellar PW

Cerebellar Afferent Fibers:

Information:

Motor areas

paravermal regions

reticular formation

pons and medulla

Cerebellar Afferent Fibers:• From the spinal cord

- anterior spinocerebellar- posterior spinocerebellar- cuneocerebellar

- Information is sent from the somatosensory receptors

Cerebellar Afferent Fibers:

From the vestibular nerve flocculonodular lobe

Receive information from the inner ear:

motion

position

• Vestibulocerebellar:

Cerebellar Afferent Fibers:

From the vestibular nerve

All afferent fibers terminate in the

flocculonodular lobe

vestibular nuclei

Table 6-1 The Afferent Cerebellar Pathways:

Pathway: Function: Origin: Destination:

Corticoponto-cerebellar

Conveys control from cerebral cortex

Cerebral lobes Via pontine nuclei and mossy fibers to cerebellar cortex

Cerebro-olivocerebellar

Via inf. olivary nuclei and climbing fibers to cerebellar cortex

Cerebroreticulo-cerebellar

Sensorimotor areas

Via reticular formation

Ant. and Post. spinocerebellar

Conveys information from muscles and joints

Muscle spindles, tendon organs, and joint receptors

Via mossy fibers to cerebellar cortex

Cuneo-cerebellar

Conveys info. from ms. and jts. of UL

Vestibular nerve Conveys information of head position and movement

Utricle, saccule, and semicircular canals

Via mossy fibers to cortex of flocculonodular lobe

Other afferents Conveys information from midbrain

Red nucleus, tectum

Cerebellar cortex

Synthesis….Questions

1. Input from the inferior olivary nucleus enters the cerebellar cortex circuitry as ______ fibers.

2. Afferents synapsing at the pontine nuclei will give rise to transverse fibers that will synapse with cerebellar cortex thru ______ cerebellar peduncle.

3. _________ lobe of the cerebellum receives input from the vestibular nuclei.

Entire output

most axons

Cerebellar Efferent Fibers:

Red nucleus

Thalamus

Vestibular complex

Reticular formation

Cerebellar Efferent Fibers:• Globose-Emboliform-Rubral Pathway• Dentothalamic PW• Fastigial Vestibular PW• Fastigial Reticular PW

* Decussation of the superior cerebellar

peduncle

Globose-Emboliform-Rubral

PW

Influences ipsilateral motor

activity

rubrospinal tract

VL nucleus thalamus

1° motor area cerebral cortex

Influences ipsilateral motor

activity

Dentothalamic PW

corticospinal fibers

decussation of pyramid

lateral vestibular nucleus Fastigial vestibular PW

Influences ipsilateral extensor muscle tone

vestibulospinal tract

Fastigial Reticular PW

reticulospinal tract

reticular formationInfluences ipsilateral

muscle tone

Table 6-2 The Efferent Cerebellar Pathways:

Pathway: Function: Origin: Destination:

Globose-emboliform-rubral

Influences ipsilateral motor activity

Globose emboliform nuclei

To CL red nucleus, then via crossed rubrospinal tract to ipsilateral motor neurons in spinal cord

Dentothalamic Influences ipsilateral motor activity

Dentate nucleus

To CL VL nucleus of thalamus, then to CL motor cerebral cortex; corticospinal tract crosses midline and controls ipsilateral motor neurons in spinal cord

Fastigial vestibular

Influences ipsilateral extensor muscle tone

Fastigial nucleus

Mainly to ipsilateral and to CL lateral vestibular nuclei; vestibulospinal tract to ipsilateral motor neurons in spinal cord

Fastigial reticular

Influences ipsilateral muscle tone

Fastigial nucleus

To neurons of reticular formation; reticulospinal tract to ipsilateral motor neurons to spinal cord

Functional Areas of the Cerebellar Cortex:

(sagittal divisions)

vermis

int

zone

lateral

zone

Vermal flocculonodular z.:Vermis/

Functional Areas of the Cerebellar Cortex:

(sagittal divisions)

vermis

int

zone

lateral

zone- control of posture, muscle

tone, locomotion, equilibrium

- projects to the fastigial nucleus

Vermal flocculonodular z.:Vermis/

Damage: ataxia

Functional Areas of the Cerebellar Cortex:

(sagittal divisions)

vermis

int

zone

lateral

zone

Paravermal/

Intermediate Zone:

Functional Areas of the Cerebellar Cortex:

(sagittal divisions)

vermis

int

zone

lateral

zone

Paravermal/

Intermediate Zone:

- Projects to nucleus interpositus

Damage:

Wide-based stance

Walking: stagger

Functional Areas of the Cerebellar Cortex:

(sagittal divisions)vermis

int

zone

lateral

zone

Lateral Zone:

- dentate nuclei thalamus motor cortex pontine nuclei, spinal cord (ant. horn cells)

Functional Areas of the Cerebellar Cortex:(sagittal divisions)

Lateral Zone:• coordination of

ipsilateral somatic motor activity

• planning of movement

• assessment of errors* Projects to the dentate

nucleus

Functional Areas of the Cerebellar Cortex:

(sagittal divisions)vermis

int

zone

lateral

zone

Lateral Zone:Lesions: cerebellar incoordination (asynergia)

Dysmetria

Past-pointing

Tremor

Dysdiadochokinesis- inability to perform regular/ rapidly alternating movements

Rebound phenomenon

Feedback Loop/s:Cortico-ponto-cerebello-dentato-

thalamo-cortical PW

(Major and Most Important)

Cerebellar Afferent Fibers:

Corticopontocerebellar PW

Information from:

1° motor and sensory areas and associative areas

1° visual cortex

Pontine nuclei

VL nucleus thalamus

1° motor area cerebral cortex

Influences ipsilateral motor

activity

Dentothalamic PW

corticospinal fibers

decussation of pyramid

Neurologic Exam: Cerebellum

Origin:

cerebral cortex

muscles, tendons, and

joints

vestibular nerve

(few)

(most)

Cerebellar Cortical Circuitry: In summary…

(few)

(most)

Inhibitory influence

lateral vestibular nucleus

Cerebellum- NO DIRECT neuronal connections with

LMN’s

- INDIRECT

Cerebellum- coordinator of precise movements

- bring about the necessary adjustments

- influence activity of LMN’s

(motor area)

Cerebellum- send back information

inhibit agonist muscles; stimulate antagonist ms.

limits voluntary movement

(motor area)

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

Clincal Neuroanatomy 7th ed., 2010

Richard S. Snell

Wolters Kluwer/Lippincott Williams and Wilkins

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

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

Thank you…