Anatomy of Cerebellum & Relevant ConnectionsNeuroanatomy block-Anatomy-Lecture 14

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● Describe the external features of the cerebellum (lobes, fissures).● Describe briefly the internal structure of the cerebellum.● List the name of cerebellar nuclei.● Relate the anatomical to the functional subdivisions of the cerebellum.● Describe the important connections of each subdivision.● Describe briefly the main effects in case of lesion of the cerebellum.

At the end of the lecture, students should be able to:

Objectives

Color guide ● Only in boys slides in Green● Only in girls slides in Purple● important in Red● Notes in Grey

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Origin : from hindbrain,lies behind Pons & Medulla Separated from them by Fourth ventricle.

Connection To Brain Stem : by inferior, middle & superior cerebellar peduncles.

External Features:It consists of two cerebellar hemispheres joined in midline by the vermisIts surface is highly convoluted forming folia separated by fissures.

Anatomical Subdivision

Anterior lobe: in front of primary fissure on the superior surface.

Flocculonodular lobe : in front of secondary

(Posterolateral) fissure on the inferior

surface .

Posterior (middle) lobe: behind primary fissure

(Between Primary & Secondary fissures

= posterolateral)

The Cerebellum

Constituents

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Internal Structure and Nuclei of Cerebellum

Deeply seated nuclei in white matter:

from medial to lateral:1. Fastigial: smallest one and most medial 2. Globose.3. Emboliform.4. Dentate: largest one and most lateral .

Inner white matter: cerebellar medulla.Afferent Fibres: (4 afferent fibers)

● Climbing fibres: (direct to purkinje cells). from inferior olivary nucleus, relay to purkinje cells ● Mossy fibres: (indirect to purkinje cells) rest of fibres:

1. From vestibular nuclei 2. From spinal cord 3. From pons They relay to granule cells which in turn relay to purkinje cellsFinally all afferent fibres passing through the medulla relay to purkinje cells in the cortex.

Axons of purkinje cells are the only axons to leave the cortex to medulla:1. The great majority of axons do not leave cerebellum & end in deep cerebellar nuclei. specially Dentate nucleus. 2. Some of axons leave cerebellum as efferent fibres.

Efferent Fibres: (3 efferent fibers) Most of efferent fibres are axons of deep cerebellar nuclei.Main efferents go to: 1. Vestibular nuclei (cerebello-vestibular tract). 2. Red nucleus (Dendato-rubro-thalamic tract). 3. Ventral lateral nucleus of thalamus (Dendato-thalamic tract).

Outer grey matter: cerebellar cortex

Divided into 3 layers:1. Outer molecular layer 2. Intermediate Purkinje

cell layer 3. Inner granular layer

also called interposed

nucleus

Functional Subdivisions Of The Cerebellum

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Archi-Cerebellum(Vestibular Part)

Paleo-Cerebellum (spinal part)

Neo-cerebellum(Cerebral Part)

Part of cerebellum flocculonodular lobe vermis & paravermis Rest of cerebellum

Nuclei Fastigial Globose & Emboliform Dentate

Afferent

from Vestibular nuclei (Vestíbulo-Cerebellar fibres) through ICP

From spinal cord (dorsal & ventral spinocerebellar tracts through ICP & SCP, respectively)

From Pons (Pontocerebellar fibres) through MCP.

Efferent

to cortical (purkinje cell) Fibres project : to Fastigial nucleus, which projects to vestibular nuclei through ICP + to Reticular formation

to globose & emboliform nuclei which project to red nucleus through SCP.

to Red nucleus but mostly to Ventral Lateral Nucleus of Thalamus (through SCP) then to motor cortex

Function

-Controls body Balance (via vestibulospinal & reticulospinal tracts).-Control of eye movement (via VO vestibulo-ocular reflex)

Controls and influence posture & muscle tone (via Rubrospinal tract).

Coordination of voluntary movements (via descending corticospinal & corticobulbar tracts or rubrospinal tract).

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Midline Lesion 2

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Cerebellar Lesions

Cerebellar ataxia causes ipsilateral: ● Incoordination of arm: intention tremor (on

performing voluntary movements)● Incoordination of leg: unsteady gait● Incoordination of eye movements: nystagmus.● Slowness of speech: dysarthria(difficulty of speech)

Loss of postural control

Unilateral Lesion

Practice Q1: The nuclei related to paleocerebellum are?

A. Globose & Dentate

B. Dentate & Fastigial c.

Globose & Emboliform

D. Emboliform & Fastigial

Q2: ______ Climbing and mossy fibers relay to ______?

A.Afferent, purkinje cells

B. Afferent, Inner granular layer

C.Efferent, Inner granular layer

D. Efferent, purkinje cells

Q3: which one of the following Archicerebellum control?

A. Body Balance

B. Posture

C. Memory and speech

D. All of the above

Q4: The cerebellum originates from the dorsal aspect of the brain stem and

overlies the ________?

A. Fourth ventricle

B. Third ventricle

C. Midline ventricle

D. Lateral ventricle

Q5: The most medial nuclei in white matter is ?

A.Fastigial nucleus

B. Globose nucleus.

C.Emboliform nucleus.

D. Dentate nucleus

Q6:To which of the following does main efferent go to?

A.Ventral medial nucleus of thalamus

B.Emboliform nucleus

C.Red nucleus

D.Globose nucleus

Q7: Neocerebellum coordinate voluntary movements via?

A.Vestibulospinal & reticulospinal tracts

B. Descending corticospinal & reticulospinal tracts

C. Vestibulospinal & cortico bulbar tracts

D.Descending corticospinal & corticobulbar tracts

Q8 From which nucleus afferent fibers go directly to purkinje cells?

A. Fastigial

B. vestibular nuclei

C. inferior olivary nucleus

D. Red nucleus

Answers: Q1(C) Q2(A) Q3(A) Q4(A) Q5(A) Q6(C) Q7(D) Q8(C) 7

Girls team :

● Ajeed Al Rashoud● Taif Alotaibi● Noura Al Turki● Amirah Al-Zahrani● Alhanouf Al-haluli● Sara Al-Abdulkarem● Renad Al Haqbani● Nouf Al Humaidhi● Jude Al Khalifah● Nouf Al Hussaini● Rahaf Al Shabri● Danah Al Halees● Rema Al Mutawa● Amirah Al Dakhilallah● Maha Al Nahdi ● Razan Al zohaifi ● Ghalia Alnufaei

Boys team:

● Mohammed Al-huqbani● Salman Alagla● Ziyad Al-jofan● Ali Aldawood● Khalid Nagshabandi● Omar Alammari● Sameh nuser● Abdullah Basamh● Alwaleed Alsaleh● Mohaned Makkawi● Abdullah Alghamdi

Team leaders

● Ateen Almutairi● Abdulrahman Shadid

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