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THE CEREBELLUM CEREBELLUM Institute of Anatomy, 2nd Medical Faculty R. Druga

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THE CEREBELLUM CEREBELLUM. Institute of Anatomy, 2nd Medical Faculty R. Druga. Cerebellar gyri = folia Cortex, subcortical white matter, nuclei. Gyri = folia, Cortex- podkorová bílá hmota – mozečková jádra. Excessive folding of the cerebellar surface (cortex). Little brain - PowerPoint PPT Presentation

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THE CEREBELLUMCEREBELLUM

Institute of Anatomy, 2nd Medical Faculty R. Druga

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Cerebellar gyri = folia

Cortex, subcortical white matter, nuclei

Excessive folding of the cerebellar surface (cortex)

Gyri = folia, Cortex- podkorová bílá hmota – mozečková jádra

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The cerebellum – relations and structure

• Little brain

• Located in the posterior cranial fossa

• Connected with the brain stem- by peduncles (inferior, middle, superior)

• Is covered by the cerebellar cortex (3 layers). Cortex is extensively folded (folia-oriented mediolaterally)

• In the white matter are the cerebellar nuclei

Fossa cranii posterior

Pedunculi cerebellares(inferior, medius, superior)

Cortex – 3 vrstvy

V bílé hmotě mozečková jádra

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MR examination

Posterior cranial fossa

MR vyšetření

Fossa cranii posterior

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Arterial

supply

AICA PICA

Arteriae

cerebellares

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Weigert

staining

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Marchi

Staining

Kluver –

Barrera

Marchiho metoda

Kluver - Barrera

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Unfolded surface

of the cerebellum

Dvourozněrná rekonstrukce povrchu (kůry)

mozečku

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Dvourozměrná

Rekonstrukce lalůčků mozečku

Dvourozměrní rekonstrukce lalůčků mozečku

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Cerebellar

lobes and

lobuli

Lobus - 3

Lobulus - 10

Mozečkové

Laloky (3) a

Lalůčky (10)

Vermis

Paravermální

oblast (zona)

Laterální část hemisféry

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CEREBELLAR NUCLEI, neurons glutamatergic, excitatory, high spontaneous activity

Mozečková jádraNeurony glutamátergní (excitační), vysoká spontánní aktivita

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Structure of the cerebellar cortex -3 layers:

I.molecular layer- inhibitory interneurons I.Molekulární vrstva – inhibiční interneurony

II. Purkyně cell layer – inhibitory projecting neurons

II. Vrstva Purkyňových buněk – inhibiční, projekční neurony

III. granular layer – prevail excitatory neurons

III. Vrstva granulárních buněk – převaha excitačních neuronů

Mozečková kůra – 3 vrstvy

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J.E. Purkyně 1837

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Cajal 1911

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R. y Cajal : Histologie du systeme nerveux, 1911.

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Santiago Ramon y Cajal 1911

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Climbing

Fibers

Olivo-cerebellar projections

(crossed)

Šplhavá vlákna

Olivocerebel.

Projekce

(zkřížená)

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Basket cells, inhibitory interneurons, GABAergic

Košíčkové buňky, inhibiční interneurony

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Mossy fibers –

Granule cells-

Paralel fibers –Purkyně cells

Climbing fiber –

Purkyně cell

Mechová

Vlákna- granulární b.

Paralelní vl.

Šplhavá

Vlákna –

Purkyňovy b.

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Afferent and efferent connections

• Tracts

• Vestibulocerebellar (from the labyrinth and vestibular nuclei)

• Spinocerebellar ant., post.,

• rostral, cuneocerebellar

• Olivocerebellar

• Reticulocerebellar

• Nucleocerebellar

• Pontocerebelar !! (cortico-ponto-cerebellar)

• Corticonuclear (from the cerebellar cortex to the nuclei)

• Vermis – nc. fastigii• Paravermal zone – nc. embol.

Nc. glob.• Lateral hemisphere – nc.

dentatus

• From cerebellar nuclei to the brain stem and to the thalamus

Aferentní a eferentní spoje kůry mozečku

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Spinocerebellar

Pathways

Posterior T1 – L2, uncrossed

ICP, proprioceptors

Anterior L3 – L5

Crossed, SCP, cutaneous signals

Rostral C4 – C8

Uncrossed, ICP

Cutaneous signals

Cuneocerebellar

C2 – T4

uncrossed

Lateral cuneate nc., propriocept.

ICP

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Dorsal (posterior) spinocerebellar

projection- uncrossedVentral (anterior) spinocerebellar projection - crossed

a b

Origin of the spinocerebellar pathways

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FMI – increased blood flow during flexion and extension of ipsilateral hand (red, orange) and foot (blue)

Funkční MR, flexe a extense ruky (červený, oranžový signál), nohy (modrý signál)

Zvýšení průtoku krve ve spinálním mozečku (lobus anterior)

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Afferent

projections

Aferentní

spoje

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Cortico- pontine pathway, 17 millions fibers

Neocortex –

ipsilat. pontine ncc. - pontocerebellar pathway –

contralateral cerebellar cortex (mossy fibers)

Kortiko-pontinní dráha

17 milionů vláken

Neocortex – ipsilaterální pontinní jádra

Pontocerebellární dráha –

Kontralaterální mozečková kůra (mechová vlákna)

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Cortico – ponto – cerebellar pathway

Cortico-ponto-cerebellar pathway

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Olivocerebellar projection

Climbing fibers

Šplhavá vlákna

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J. Eccles 1967

Nobel Prize in Physiology and medicine 1963

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AFFERENTS TO THE CEREBELLAR CORTEX I.

• Climbing fibers – inferior olive (each P.cell receives only 1 c.f., many synapses with P.c.), excitatory (glutamate), firing frequency of the c.f. is very low (1 impulse/sec), c.f. elicit burst of action potentials in the P.c.

• C.f. inform about errors in the execution of movements – error indicators !!

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AFFERENTS TO THE CEREBELLAR CORTEX II

• Mossy fibers - spinal cord, RF, pontine nuclei, ncc. cranial nerves.

• End in the granular layer and each of which contacts large number of granular neurons. Granular cell axon contacts large number of P. c. via paralel fibers.

• Mossy fibers are excitatory (glutamate).

• Each mossy fiber influences many P.c. but the excitatory effect is weak. Many mossy fibers must be active together to provide sufficient excitation to fire a P.c.

• Mossy fibers provide precisely graded information about movements, skin stimulations, joint position and about motor comands issued from the cerebral cortex.

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Efferent connections of the cerebellar cortex

Cerebellar cortex – cerebellar nuclei vermis – nc. fastigii, vestibular ncc.

pavermal zone – emboliformis, globose ncc. lateral hemisphere – dentate nc.

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Corticonuclear projection

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Efferent connections of the cerebellar nuclei

• Fastigial nucleus – vestibular nuclei, reticular formation

• Emboliformis + globosus nucleus -.reticular formation, nc. ruber, thalamus

• Nucleus dentatus – nc. ruber, contralateral thalamus (ventrolateral nucleus, intralaminar thalamic nuclei, ventral anterior nc.,

• Ventrolateral nucleus – primary motor cortex (area 4)

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Thalamus

Nc. Ventralis

Lateralis

Nc. VL –

Motor cortex

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Cortico-ponto-cerebello-cortical circuit

(Transcerebellar

Circuit)

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Mozečkové syndromy

• Vestibulární mozeček a vermis – poruchy rovnováhy, stoje a chůze, chůze o široké bazi, nystagmus

• Spinální mozeček – kontroluje axiální svalstvo a proximální svaly končetin. Při poškození zvýšení tonu extensorů.

• Pontinní mozeček (hemisféry) - přestřelování pohybů (hypermetrie, prst – lalůček, prst- špička nosu). Adiadochokinéza, třes(méně než 5 Hz- zhoršuje se na konci zacíleného pohybu)), poruchy řeči a výslovnosti (dysartrie, skandovaná řeč), poruchy plánování, uvažování (kognitivní poruchy).

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Paleocerebellar lesions (syndrome)

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Neocerebellar syndrome (lesion of the hemisphere)

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