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Cerebellum Roosindu Peris & Yatharth Verma University of ManchesterEmbryology first • Anterior part of neural tube develops to form the prosencephalon, mesencephalon and rhombencephalon • The rhombencephalon splits into a superior and inferior part known as metencephalon and myelencephalonrespectively • Cerebellum develops from themetencephalon (superior part)Location Location Location! • Inferior to occipital and temporal lobe • Lies in the posterior cranial fossa, at the level of the pons • Pons and cerebellum are separated by the fourth ventricleLobes • Contains 3 lobes : anterior, posterior and flocculonodular lobe • These lobes are separated by the primary fissure and posterolateral fissureGross structureInternal structureCerebellar Nuclei • Lie deep within cerebellar white matter, above the roof of the 4th ventricle • 4 bilaterally-paired nuclei • Medial to lateral: • Fastigial nucelus • Globose nucleus • Emboliform nucleus • Dentate nucleus*Functional Divisions* • Cerebrocerebellum(Neocerebellum) – cerebellar hemisphere + dentate nuclei • Spinocerebellum (Paleocerebellum) – vermis + paravermis + globose + emboliform nuclei • Vestibulocerebellum(Archicerebellum) – flocculonodular lobe+ fastigialZones Cerebrocerebellum (Neocerebellum) • Concerned with muscle co-ordination • Afferent pathways mainly come from the nuclei in the pons (pontocerebellar fibers) • Afferent : cortex of cerebrum>>> corticopontine fibers >>pons nuclei >>pontocerebellar fibers >>> cortex of cerebellum • Pontocerebellar fibers cross to opposite side of cerebellum through middle cerebellar peduncle • Efferent fibersfrom this part go to the dentate nucleus • Dentate nucleus >> contralateral red nucleus + thalamus >>> motor cortex in frontal lobe • Fibers starting from dentate going up to thalamus make up most of superior cerebellar peduncle • Effects of neocerebellum are exerted via the corticospinal tracts Spinocerebellum (Paleocerebellum) • Influences muscle tone and posture • Afferents are from dorsal and ventral spinocerebellar tracts and enter the superior cerebellar pedunclesnd respectively • Afferent terminates in the ipsilateral vermis (and paravermis) • Efferents cerebellar cortex >>globose +emboliform (+fastigial nuclei) • Globose and emboliform >>> superior cerebellar peduncle >>>contralateral red nucleus >>> descending rubrospinal tract Vestibulocerebellum (Archicerebellum) • Maintains balance and equilibrium • Connects with the vestibularand reticular nuclei via the inferior peduncle • Afferent : vestibular system >>> vestibular nuclei >>>> ipsilateral flocculonodular cortex • Efferent: cortex of cerebellum >>> fastigial >>> vestibular + reticular nuclei >>> vestibulospinal and reticulospinal tracts • Many fastigial efferentscross to the contralateral side of brainstem, forming the descending vestibulospinal and reticulospinalCerebellar Histology • Cerebellum functions to maintain balance, equilibrium, muscle tone, and muscle coordination • Layer of gray matter at the periphery is called the cerebellar cortex • Histologically the cortex is divided into 3 layers: • Molecular layer • Purkinje cell layer • Granular layerCerebellar Cortex Layers • Molecular layer: • Purkinje cells, basket cells andes of unmyelinated axons from the granular layer • Purkinje cell layer: • Contains Purkinje cells which are found only in the cerebellum • Myelinated axons project into cerebellar white matter • Only cell that sends information out of (GABA)rebellum and is always inhibitory • Granular layer: • Contains small granule cells and glomeruli (cerebellar islands)Cerebellar Vascular Supply • Supplied by the Anterior inferior, posterior inferior and superior cerebellar arteries • Arteries form superficial anastomoses on the cortical surface • PICA supplies choroid plexus of 4th ventricleFrom which structure does the cerebellum develop? • Metencephalon • Myelencephalon • Prosencephalon • MesencephalonWhich lobes are seperated by the primary fissure? • Frontal and parietal • Flocculonodular and Posterior • Anterior and posterior • Flocculonodular and anteriorWhich cerebellar nuclei are part of the paleocerebellum? • Dentate nucleus only • Fastigial nucleus only • Emboliform nucleus and Dentate nucleus • Emboliform nucleus and Globose nucleus • Fastigial nucleus and Emboliform nucleusWhich neurotransmitter is used for output by the Purkinjie cells? • Glutamate • Noradrenaline • Dopamine • Serotonin • GABAWhich artery supplies the choroid plexus of the 4th ventricle? • Basilar artery • PICA • AICA • Superior Cerebellar Artery • Posterior choroidal arteryReferences 1. https://www.ruf.rice.edu/~lngbrain/cglidden/ 2. https://teachmeanatomy.info/neuroanatomy/structures/cerebellum/ 3. https://www.amboss.com/us/knowledge/Cerebellum/ 4. https://www.sciencedirect.com/topics/neuroscience/cerebellum 5. https://slideplayer.com/slide/10390794/ 6. https://doctorlib.info/anatomy/neuroanatomy-illustrated-colour-text/11.html 7. https://www.zookal.com/solutions-library/correctly-label-the-following-anatomical-features-of-the-cerebellum-and- 808068770? 8. https://juniperpublishers.com/apbij/pdf/APBIJ.MS.ID.555552.pdf 9. https://sisu.ut.ee/histology/cerebellum 10. https://ranzcrpart1.fandom.com/wiki/Arterial_supply_to_brain:Cerebellar_arteries_(SCA,_AICA,_PICA) 11. http://www.dontbeasalmon.net/archives/2010/09/week-202-circle.html 12. TEXTBOOK OF HISTOLOGY, FOURTH EDITION-INTERNATIONAL EDITION 13. Crossman’s Neuroanatomy