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The cerebellum is located in the posterior cranial fossa below the tentorium cerebelli. It has three lobes - flocculonodular, anterior and posterior - and is divided into a central vermis and lateral hemispheres. It receives input from the spinal cord and cerebral cortex and controls balance, muscle tone and coordination of voluntary movements through its outputs to the vestibular system and motor areas of the brainstem and cortex.

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Cerebellum
Cerebellum • Largest part of hindbrain • About 150 grams • Separated from medulla & pons by a cavity – fourth ventricle • It controls • Balance • Muscle tone • Co-ordination of voluntary movements
Cerebellum • Position • In the posterior cranial fossa • Below tentorium cerebelli • Tentorium cerebelli separates • Cerebellum from occipital lobe of cerebrum
External features • 3 parts • 2 surfaces • 2 notches • 2 fissures
Parts of cerebellum • Has 2 hemispheres • Connected by vermis • Vermis • Also divided into • Superior vermis • Inferior vermis • Present in deep depression called valecula
• Has 2 surfaces • Superior • Inferior • Separated by • Horizontal fissure Surfaces
Notches • 2 notches • Anterior notch • V – shaped • Lies behind the pons & medulla • Posterior notch • Narrow • Lodges falx cerebelli
Fissures • Primary fissure • Lies in superior fissure • V – shaped (apex facing posteriorly) • Separates anterior lobe from posterior lobe • Posterolateral fissure • First fissure to appear • Lies in inferior surface at anterior aspect • Separates flocculonodular lobe from other parts of cerebellum • Horizontal fissure • Lies at the junction of superior and inferior surfaces
Lobes and fissures • Three lobes • Flocculonodular lobe • Anterior • Posterior lobe • Two deep fissures • Primary fissure • Posterolateral fissure
• Horizontal fissure • Separates superior & inferior vermis • Primary fissure • Separates anterior lobe from superior part of posterior lobe • Parts of superior vermis Lingula Central lobule Superior vermis Culmen Declive Folium
Inferior vermis • Present in deep depression called valeculla • Posterolateral fissure • Separates inferior part of posterior lobe and flocculonodular lobe Nodule Uvula Pyramid Tuber
cerebellum.pptx
Applied anatomy • Tonsil of cerebellum • Elevated masses on inferior surface of hemispheral portion • Just nearby foramen magnum • If intracranial pressure raises • Tonsil pushed through foramen magnum • Compresses medulla
Internal structures • Gray matter • Cerebellar cortex • Cerebellar nuclei • Dentate nucleus • Fastigial nucleus • Emboliform nucleus • Globose nucleus • White matter
Cortex & nuclei • Grey matter on surface • Folded and known as folia • Transverse fissures • Grey matter in deep (inside) • 4 in number
Cortex - layers • 3 layers • Molecular layer • Has dendrites of Purkinje cell and parallel fibres (axons of granule cells) • Neurons are • Basket & stellate cells • Purkinje layer • Single row of Purkinje cells • Dendrites synapse with • Stellate, basket neurons • Parallel fibre of granule cells • Climbing fibres • Axons • Only cortex neurons contact with intracerbellar nuclei • Granular layer • Golgi, granule
Cortex - neurons • Granule cells • Receives mossy fibres (excitatory) • Sends fibres (parallel fibres) to Purkinje, basket and stellate cells (excitatory) • Stellate, basket and golgi cells • Inhibitory interneurons • Purkinje cells • Only output from cortex • Inhibitory to neurons in deep cerebellar nuclei
Dentate nucleus • Crumpled bag like • Hilum facing medially • Largest deep nucleus • Recent (modern) nucleus • Receives fibres from • Ipsilateral neocerebellar cortex (lateral part of cerebellar hemisphere) • Collaterals from mossy & climbing fibres • Sends fibres to • Red nucleus and thalamus
• Globosus & emboliformis • More recent nuclei • Receives from paravermal cortex (Paleocerebellum) • Sends fibres to red nucleus • Fastigial nucleus • Smallest • Receives fibres from • Vermal & floculo-nodular lobe • Sends fibres to • Vestibular & reticular formation
Peduncles • Inferior cerebellar peduncle • Connect with medulla • Contain both afferent and efferent fibers • Middle cerebellar peduncle • Connect with pons • Contain afferent fibers • Superior cerebellar peduncle • Connect with midbrain • Contain mostly efferent fibers
Superior cerebellar peduncle • Connects with midbrain • Contains both afferent & efferent • Afferent • Anterior spinocerebellar • Tectocerbellar • Rubrocerebellar • Efferent • Dentatothalamic • Dentatorubral
• Connects pons with cerebellum • Contains only afferent fibres • Cortico-ponto-cerebellar Middle cerebellar peduncle
Inferior cerebellar peduncle • Otherwise restiform body • Fibres passing • Afferent • Posterior spinocerebellar • Posterior external arcuate (cuneocerebellar) • Anterior external arcuate • Vestibulocerebellar • Olivocerebellar • Reticulocerebellar • Efferent • Cerebellovestibular • Cerebelloolivary • Cerebelloreticular
Functional lobes • Based on connections & functions • 3 lobes • Archicerebellum • Paleocerebellum • Neocerebellum
Archicerebellum • Phylogenetically oldest • Flocculonodular lobe • Control on • Balance & eye movements • Lesions • Trunk ataxia • Staggering gait • Nystagmus • Involuntary rhythmic side-to-side, up and down or circular motion of the eyes
Archicerebellum - connections • Afferents • From vestibular nuclei • Vestibulo-cerebellar tract • Efferents • Cerebello-vestibular • Cortex & fastigial nuclei to vestibular nuclei • Vestibulospinal • Medial longitudinal • Cerebello-reticular • To pontine & meullary reticular formation • Connected to motor neurons of Spinal cord
Paleocerebellum • Also called spinocerebellum • Has vermis & paravermis (except flocculus) • Related to central part of body • Regulation of body movements • Doing body movement error correction • Regulates muscle tone • Lesion • Ataxia – inability in maintaining balance (while walking)
Paleocerebellum- connections • Afferents • Spinocerebellar (anterior & posterior) • Cuneocerebellar • Efferents • Cerebello rubral • From interposed (Globose & emboliform) nuclei to red nucleus • Rubro-spinal
Neocerebellum - cerebrocerebellum • Formed by lateral part of hemispheres • Planning movement & motor learning • Muscle co-ordination • Lesions • Intention tremor • Dysmetria
Neocerebellum - connections • Afferents • From cerebral cortex via pontine nuclei • Cortico-pontine-cerebellar pathway • Efferents • Neocortex to dentate nucleus • Dentato-rubro-thalamo- cortical • From cortex to spinal cord & cranial nerve nuclei • Via corticobulbar & cortico spinal tracts
Blood supply • Superior cerebellar artery • From basilar • Anterior inferior cerebellar artery • From basilar • Posterior inferior cerebellar artery • From vertebral
cerebellum.pptx
cerebellum.pptx

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cerebellum.pptx

  • 2. Cerebellum • Largest part of hindbrain • About 150 grams • Separated from medulla & pons by a cavity – fourth ventricle • It controls • Balance • Muscle tone • Co-ordination of voluntary movements
  • 3. Cerebellum • Position • In the posterior cranial fossa • Below tentorium cerebelli • Tentorium cerebelli separates • Cerebellum from occipital lobe of cerebrum
  • 4. External features • 3 parts • 2 surfaces • 2 notches • 2 fissures
  • 5. Parts of cerebellum • Has 2 hemispheres • Connected by vermis • Vermis • Also divided into • Superior vermis • Inferior vermis • Present in deep depression called valecula
  • 6. • Has 2 surfaces • Superior • Inferior • Separated by • Horizontal fissure Surfaces
  • 7. Notches • 2 notches • Anterior notch • V – shaped • Lies behind the pons & medulla • Posterior notch • Narrow • Lodges falx cerebelli
  • 8. Fissures • Primary fissure • Lies in superior fissure • V – shaped (apex facing posteriorly) • Separates anterior lobe from posterior lobe • Posterolateral fissure • First fissure to appear • Lies in inferior surface at anterior aspect • Separates flocculonodular lobe from other parts of cerebellum • Horizontal fissure • Lies at the junction of superior and inferior surfaces
  • 9. Lobes and fissures • Three lobes • Flocculonodular lobe • Anterior • Posterior lobe • Two deep fissures • Primary fissure • Posterolateral fissure
  • 10. • Horizontal fissure • Separates superior & inferior vermis • Primary fissure • Separates anterior lobe from superior part of posterior lobe • Parts of superior vermis Lingula Central lobule Superior vermis Culmen Declive Folium
  • 11. Inferior vermis • Present in deep depression called valeculla • Posterolateral fissure • Separates inferior part of posterior lobe and flocculonodular lobe Nodule Uvula Pyramid Tuber
  • 13. Applied anatomy • Tonsil of cerebellum • Elevated masses on inferior surface of hemispheral portion • Just nearby foramen magnum • If intracranial pressure raises • Tonsil pushed through foramen magnum • Compresses medulla
  • 14. Internal structures • Gray matter • Cerebellar cortex • Cerebellar nuclei • Dentate nucleus • Fastigial nucleus • Emboliform nucleus • Globose nucleus • White matter
  • 15. Cortex & nuclei • Grey matter on surface • Folded and known as folia • Transverse fissures • Grey matter in deep (inside) • 4 in number
  • 16. Cortex - layers • 3 layers • Molecular layer • Has dendrites of Purkinje cell and parallel fibres (axons of granule cells) • Neurons are • Basket & stellate cells • Purkinje layer • Single row of Purkinje cells • Dendrites synapse with • Stellate, basket neurons • Parallel fibre of granule cells • Climbing fibres • Axons • Only cortex neurons contact with intracerbellar nuclei • Granular layer • Golgi, granule
  • 17. Cortex - neurons • Granule cells • Receives mossy fibres (excitatory) • Sends fibres (parallel fibres) to Purkinje, basket and stellate cells (excitatory) • Stellate, basket and golgi cells • Inhibitory interneurons • Purkinje cells • Only output from cortex • Inhibitory to neurons in deep cerebellar nuclei
  • 18. Dentate nucleus • Crumpled bag like • Hilum facing medially • Largest deep nucleus • Recent (modern) nucleus • Receives fibres from • Ipsilateral neocerebellar cortex (lateral part of cerebellar hemisphere) • Collaterals from mossy & climbing fibres • Sends fibres to • Red nucleus and thalamus
  • 19. • Globosus & emboliformis • More recent nuclei • Receives from paravermal cortex (Paleocerebellum) • Sends fibres to red nucleus • Fastigial nucleus • Smallest • Receives fibres from • Vermal & floculo-nodular lobe • Sends fibres to • Vestibular & reticular formation
  • 20. Peduncles • Inferior cerebellar peduncle • Connect with medulla • Contain both afferent and efferent fibers • Middle cerebellar peduncle • Connect with pons • Contain afferent fibers • Superior cerebellar peduncle • Connect with midbrain • Contain mostly efferent fibers
  • 21. Superior cerebellar peduncle • Connects with midbrain • Contains both afferent & efferent • Afferent • Anterior spinocerebellar • Tectocerbellar • Rubrocerebellar • Efferent • Dentatothalamic • Dentatorubral
  • 22. • Connects pons with cerebellum • Contains only afferent fibres • Cortico-ponto-cerebellar Middle cerebellar peduncle
  • 23. Inferior cerebellar peduncle • Otherwise restiform body • Fibres passing • Afferent • Posterior spinocerebellar • Posterior external arcuate (cuneocerebellar) • Anterior external arcuate • Vestibulocerebellar • Olivocerebellar • Reticulocerebellar • Efferent • Cerebellovestibular • Cerebelloolivary • Cerebelloreticular
  • 24. Functional lobes • Based on connections & functions • 3 lobes • Archicerebellum • Paleocerebellum • Neocerebellum
  • 25. Archicerebellum • Phylogenetically oldest • Flocculonodular lobe • Control on • Balance & eye movements • Lesions • Trunk ataxia • Staggering gait • Nystagmus • Involuntary rhythmic side-to-side, up and down or circular motion of the eyes
  • 26. Archicerebellum - connections • Afferents • From vestibular nuclei • Vestibulo-cerebellar tract • Efferents • Cerebello-vestibular • Cortex & fastigial nuclei to vestibular nuclei • Vestibulospinal • Medial longitudinal • Cerebello-reticular • To pontine & meullary reticular formation • Connected to motor neurons of Spinal cord
  • 27. Paleocerebellum • Also called spinocerebellum • Has vermis & paravermis (except flocculus) • Related to central part of body • Regulation of body movements • Doing body movement error correction • Regulates muscle tone • Lesion • Ataxia – inability in maintaining balance (while walking)
  • 28. Paleocerebellum- connections • Afferents • Spinocerebellar (anterior & posterior) • Cuneocerebellar • Efferents • Cerebello rubral • From interposed (Globose & emboliform) nuclei to red nucleus • Rubro-spinal
  • 29. Neocerebellum - cerebrocerebellum • Formed by lateral part of hemispheres • Planning movement & motor learning • Muscle co-ordination • Lesions • Intention tremor • Dysmetria
  • 30. Neocerebellum - connections • Afferents • From cerebral cortex via pontine nuclei • Cortico-pontine-cerebellar pathway • Efferents • Neocortex to dentate nucleus • Dentato-rubro-thalamo- cortical • From cortex to spinal cord & cranial nerve nuclei • Via corticobulbar & cortico spinal tracts
  • 31. Blood supply • Superior cerebellar artery • From basilar • Anterior inferior cerebellar artery • From basilar • Posterior inferior cerebellar artery • From vertebral