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Anatomy of Cerebellum & Relevant Connections

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Anatomy of Cerebellum & Relevant Connections Anatomy of Cerebellum & Relevant Connections Neuroanatomy block-Anatomy-Lecture 14 Editing file Objectives At the end of the lecture, students should be able to: ● 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. Color guide ● Only in boys slides in Green ● Only in girls slides in Purple ● important in Red ● Notes in Grey The Cerebellum 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 vermis Its surface is highly convoluted forming folia separated by fissures. Anatomical Subdivision Posterior (middle) lobe: Flocculonodular lobe : Anterior lobe: in front behind primary fissure in front of secondary of primary fissure on (Between Primary & (Posterolateral) the superior surface. Secondary fissures fissure on the inferior = posterolateral) surface . 3 Constituents Internal Structure and Nuclei of Cerebellum Inner white matter: cerebellar medulla. Afferent Fibres: (4 afferent fibers) Deeply seated nuclei in ● Outer grey matter: Climbing fibres: (direct to purkinje cells). from inferior olivary nucleus, relay to purkinje cells white matter: ● cerebellar cortex Mossy fibres: (indirect to purkinje cells) rest of fibres: from medial to lateral: Divided into 3 layers: 1. From vestibular nuclei 2. From spinal cord 3. From pons 1. Fastigial: smallest one 1. Outer molecular layer They relay to granule cells which in turn relay to purkinje cells and most medial Finally all afferent fibres passing through the medulla relay to purkinje cells in the cortex. also called 2. Intermediate Purkinje 2. Globose. interposed cell layer 3. Emboliform. nucleus 3. Inner granular layer Axons of purkinje cells are the only axons to leave the cortex to medulla: 4. Dentate: largest one 1. The great majority of axons do not leave cerebellum & end in deep cerebellar nuclei. specially and most lateral . 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). 4 Functional Subdivisions Of The Cerebellum Archi-Cerebellum Paleo-Cerebellum Neo-cerebellum (Vestibular Part) (spinal part) (Cerebral Part) Part of flocculonodular lobe vermis & paravermis Rest of cerebellum cerebellum Nuclei Fastigial Globose & Emboliform Dentate from Vestibular nuclei From spinal cord (dorsal & From Pons (Pontocerebellar fibres) (Vestíbulo-Cerebellar fibres) ventral spinocerebellar through MCP. Afferent through ICP tracts through ICP & SCP, respectively) to cortical (purkinje cell) to globose & emboliform to Red nucleus but mostly to Fibres project : to Fastigial nuclei which project to red Ventral Lateral Nucleus of Efferent nucleus, which projects to nucleus through SCP. Thalamus (through SCP) then to vestibular nuclei through motor cortex ICP + to Reticular formation -Controls body Balance Controls and influence Coordination of voluntary (via vestibulospinal & posture & muscle tone movements reticulospinal tracts). (via Rubrospinal tract). (via descending corticospinal & Function -Control of eye movement corticobulbar tracts or rubrospinal (via VO vestibulo-ocular tract). reflex) 5 Cerebellar Lesions Midline Lesion 2 Unilateral Lesion Cerebellar ataxia causes ipsilateral: Loss of postural control ● Incoordination of arm: intention tremor (on performing voluntary movements) 1 ● Incoordination of leg: unsteady gait ● Incoordination of eye movements: nystagmus. ● Slowness of speech: dysarthria(difficulty of speech) 6 Practice Q1: The nuclei related to paleocerebellum are? Q5: The most medial nuclei in white matter is ? A. Globose & Dentate A.Fastigial nucleus B. Dentate & Fastigial c. B. Globose nucleus. Globose & Emboliform C.Emboliform nucleus. D. Emboliform & Fastigial D. Dentate nucleus Q2: ______ Climbing and mossy fibers relay to ______? Q6:To which of the following does main efferent go to? A.Afferent, purkinje cells A.Ventral medial nucleus of thalamus B. Afferent, Inner granular layer B.Emboliform nucleus C.Efferent, Inner granular layer C.Red nucleus D. Efferent, purkinje cells D.Globose nucleus Q3: which one of the following Archicerebellum control? Q7: Neocerebellum coordinate voluntary movements via? A. Body Balance A.Vestibulospinal & reticulospinal tracts B. Posture B. Descending corticospinal & reticulospinal tracts C. Memory and speech C. Vestibulospinal & cortico bulbar tracts D. All of the above D.Descending corticospinal & corticobulbar tracts Q4: The cerebellum originates from the dorsal aspect of the brain stem and Q8 From which nucleus afferent fibers go directly to purkinje cells? overlies the ________? A. Fastigial A. Fourth ventricle B. vestibular nuclei B. Third ventricle C. inferior olivary nucleus C. Midline ventricle D. Red nucleus D. Lateral ventricle Answers: Q1(C) Q2(A) Q3(A) Q4(A) Q5(A) Q6(C) Q7(D) Q8(C) 7 Members board Team leaders ● Abdulrahman Shadid ● Ateen Almutairi Girls team : Boys team: ● Ajeed Al Rashoud ● Mohammed Al-huqbani ● Taif Alotaibi ● Salman Alagla ● Noura Al Turki ● Ziyad Al-jofan ● Amirah Al-Zahrani ● Ali Aldawood ● Alhanouf Al-haluli ● Khalid Nagshabandi ● Sara Al-Abdulkarem ● Omar Alammari ● Renad Al Haqbani ● Sameh nuser ● Nouf Al Humaidhi ● Abdullah Basamh ● Jude Al Khalifah ● Alwaleed Alsaleh ● Nouf Al Hussaini ● Mohaned Makkawi ● Rahaf Al Shabri ● Abdullah Alghamdi ● Danah Al Halees ● Rema Al Mutawa ● Amirah Al Dakhilallah ● Maha Al Nahdi Contact us: ● Razan Al zohaifi ● Ghalia Alnufaei Editing file most probably you don't need this .
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