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CEREBELLUM

DR. SAHEMA @ ZAR CHI THENT PROF MADYA DR. FAIZAH OTHMAN DEPARTMENT OF ANATOMY FACULTY OF MEDICINE UKM


Objectives • Describe the different parts of the cerebellum • Describe the locations. • Correlate the anatomical lobes, functional lobes and the main function of the cerebellum • Describe the internal features including the nuclei. • Describe the main afferent and efferent connections and the components of the 3 peduncles • Apply anatomical knowledge to correlate with cerebellar disorder.


MAJOR DIVISIONS OF CNS • BRAIN – Cerebrum - Cerebellum

• SPINAL CORD


CEREBELLUM • CEREBELLUM is one of the three major motor control centres of the brain:

•Cerebral cortex •Basal ganglia •Cerebellum


CEREBELLUM • • • •

“Little brain” Divides into hemispheres Cortex surrounds the hemispheres Function – Balance – Posture – Movement

• Unconsciously controls voluntary muscles to produce coordinated and smooth action. • Each cerebellar hemisphere controls ipsilateral side of the body


• • • •

Location Division Peduncle Internal structure


Cerebellum“ little brain ” • within the posterior fossa, • straddles the brainstem and forms the roof of the 4th ventricle • two cerebellar hemisphere joined by vermis


Cerebral aqueduct

Cerebellum

Midbrain

Pons IV Ventricle Medulla oblongata


CEREBELLUM VERMIS

HEMISPHERE


SUPRA TENTORIUM

TENTORIUM

INFRA TENTORIUM The tentorium cerebelli

“ tent of the cerebellum ”

separates the cerebellum from the occipital lobes of the cerebrum.


LOBES • ANATOMICAL

• FUNCTIONAL

– FLOCCULONODULAR

– ARCHICEREBELLUM

– ANTERIOR LOBE

– PALEOCEREBELLUM

– POSTERIOR LOBE

– NEOCEREBELLUM


Divisions of the cerebellum Inferior View

Superior Surface

Ant Lobe flocculus nodulus

Ant Lobe

Post Lobe

Post Lobe

three main lobes

Schematic

Ant Lobe

Ant Lobe

nodulus Post Lobe

Post Lobe

flocculus

nodulus


Anatomical divisions of the Cerebellum From Superior surface

From Inferior surface

• Anterior lobe

• Anterior lobe

• Posterior lobe

• Posterior lobe

• Separated by primary fissure

• Flocculonodular lobe


ANATOMICAL


Anterior lobe

Posterior lobe

Pons

Flocculonodular lobe Medial view


ANATOMICAL

Anterior lobe Primary fissure

Posterior lobe


ANATOMICAL Anterior lobe Primary fissure Posterior lobe

Horizontal fissure


ANATOMICAL


ANATOMICAL

Posterior lobe

Superior vermis

Horizontal fissure

Inferior vermis


ANATOMICAL


ANATOMICAL

Superior CP

Anterior lobe

Middle CP

Postero lateral fissure

CP = cerebellar peduncle

Inferior CP

Posterior lobe

Flocculo nodular lobe


Anterior lobe Vermis

Superior CP Middle CP

Flocculonodular lobe

Inferior CP

Posterior lobe

Ventral view


FISSURES • ANATOMICAL – POSTERIOR LOBE

– Posterolateral fissure – FLOCCULO NODULAR LOBE


ANATOMICAL

• Anterior lobe – – – – –

pyramid uvula lingula central lobule culmen

• Posterior lobe – declive – folium – tuber


FUNCTIONAL Paleocerebellum-posture

Neocerebellum-coordination

Archicerebellum-equilibrium


• Peduncle

• Connects to

– SUPERIOR

– MIDBRAIN

– MIDDLE

– PONS

– INFERIOR

– MEDULLA


SCP

MCP

ICP

Midbrain

Pons

Medulla


Internal structure • Gray matter • White matter


Cerebellum

outer cortex, inner white matter with embedded deep nuclei


Gray matter • Cerebellar cortex – – – –

3 layers Molecular Purkinje Granular

• Cerebellar nuclei – – – –

Dentate Emboliform Globose Fastigeal


Layers of cerebellar cortex

Mol

Gr

Molecular

Cortex

WM Granular

Outer

Molecular layer

Stellate cells, Basket cells

Middle

Purkinje cell layer

Purkinje cells

Inner

Granular layer

Granule cells, Golgi cells


Purkinje cells • flaskshaped cell, single layered Dendrites - molecular layer - profuse branching - dendritic spines – Axon - synapse with DCN - basket & stellate cells - vestibular nuclei


Climbing fibres • from inferior olive • direct action on individual Purkinje cell • powerful , sharply localised

Basket cells, stellate cells, Golgi cells act as inhibitory interneurons.

Mossy fibres • from spinal cord / brain stem centres • indirect action on Purkinje cells via granule cells • diffuse ( thousands of Punkinje cells may be excited )


molecular purkinje granular

Climbing fibres - Inf Oliv Nuc Mossy fibres – spinal cord & brainstem

To brain stem & thalamus

Cerebellar nucleus


• Cerebellar cortex and Cerebellar nuclei

F G

E

Dentate Emboliform

Globose Fastigeal

D


Deep Cerebellar Nuclei • receive afferent information from – Inhibitory axons ( from Purkinje cells of cortex )

– Excitatory axons ( from climbing and mossy fibres )


White matter • VERMIS-arbor vitae • Intrinsic fibres • Cerebellar afferent fibres- enter via MCP & ICP • Cerebellar efferent fibres– From DEG-via SCP – from fastigeal via ICP


Cerebellar white fibres I.

Internal circuitry of the cerebellum •

• •

do not leave cerebellum, interconnect different regions of the organ some connect same side some connect two cerebellar hemisphere

II. Cerebellar afferents •

enter via MCP & ICP

III. Cerebellar efferents • •

From DEG-via SCP From fastigeal via ICP


Cerebellar Afferent Fibres • Cerebral cortex – Corticopontocerebella r – Cerebroolivocerebellar – Cerebroreticulo cerebellar

• Vestibular nucleus – Vestibulocerebellar (flocculonodular lobe)

• Spinal cord – ANT Spinocerebellar – POST Spinocerebellar – Cuneocerebellar

• Others – Red nucleus, tectum


Spinal cord


Cerebellar Efferent Fibres • Globose-emboliform-rubral pathway synapse with cells of red nucleus give rise to rubrospinal tract • Dentatothalamic pathway ventrolateral nucleus of thalamus • Fastigial vestibular pathway lateral vestibular nucleus give rise to vestibulospinal tract • Fastigial reticular pathway


SUMMARY of NUCLEAR CONNEXIONS LOBES

CERE BELLAR NUCLEUS

NUCLEUS & EFFERENT TRACT

ARCHI(floc culonodular)

Fastigeal

Reticular formation reticulospinal Vestibulo nuc - vestibulospinal tract

PALEO(ant)

Emboliform Globose

Red nucleus-rubrospinal,

NEO (post)

Dentate

VL-thalamus-motor cortex corticospinal


Dysfunction of cerebellum • Equilibrium – staggering gait • Muscle tone & posture hypotonia • Coordination – tremor, ataxia, dysdiadochokinesia, dysmetria, nystagmus, dysarthria • Hypotonia • Loss of influence of the cerebellum on the activities of the cerebral cortex.


CLASSICAL SIGNS • Hypotonia • Reflexes • ( rebound phenomenon) • Ataxia • muscles contract irregularly and weakly • muscle groups fail to work harmoniously • no proper coordination • Tremors • Decomposition of movement • Dysdiadochokinesia • Nystagmus • Dysarthria • Postural changes / alteration of gait • wide base / staggering gait


REBOUND PHENOMENON

b - Normal

c – Cerebellar lesion


DYSDIADOCHOKINESIA


ATAXIA & INTENTION TREMOR


Paleocerebellum-posture

Midline lesion-loss of postural control Unilateral – ipsilateral incoordination of limb Bilateral – dysarthria, bilateral incoordination of limb Eye movement - nystagmus

Neocerebellum-coordination

Archicerebellum-equilibrium


• Midline lesion-loss of postural control – VERMIS SYNDROME

• Unilateral – ipsilateral incoordination of limb, may fall to the side of lesion – CEREBELLAR HEMISPHERE SYNDROME

• Bilateral – speech (dysarthria), eye movement (nystagmus), bilateral incoordination of limb – Common diseases involving cerebellum • Alcoholism, trauma, tumour, infection, congenital


THANK YOU


Cerebellum