Anatomy of cerebellum

1. CEREBELLUM DR MANAH CHANDRA CHANGMAI BY

2. GROSS ANATOMY OF CEREBELLUM Location: The term cerebellum is from “ latin meaning ” the little brain .It is a part of the hindbrain situated in the posterior cranial fossa . It is also present behind the pons and medulla ablongata,seperated from two structures by the cavity of fourth ventricle. It is covered by tentorium cerebelli and is connected to brain stem by three cerebellar peduncles. In adults the weight ratio between cerebellum and cerebrum is 1:10,Infants 1:20

3. Consists of two laterally, large hemisphere which are united by midline vermis . Cerebellar surface is divided by numerous curve transverse fissures giving it a laminated appearance One conspicious fissure “ horizontal fissure ” extends around dorsolateral border of each hemisphere from middle cerebellar peduncle to vallecula,seperating superior and inferior surface Horizontal fissure Vermis Hemisphere Superior surface Anatomy of cerebellum......contd.

4. The deepest fissure in the vermis is primary fissure , which curves ventrolaterally in the superior surface of the cerebellum to meet horizontal fissure. Primary fissure divides the cerebellum into anterior and posterior lobe. Primary fissure Anterior lobe Posterior lobe Primary fissure External surface of cerebellum

5. Horizontal fissure vermis Primary fissure Anterior lobe Posterior lobe Hemisphere External surface of cerebellum

6. Fourth ventricle Arbor vitae cerebelli Arbor vitae • In latin “ tree of life ” it is the white matter of the white matter of cerebellum. • It is so called because of the tree like appearance. • It brings sensory and motor sensation to and from cerebellum.

7. The cerebellum is connected to Brain stem by three peduncles Superior cerebellar peduncle Midbrain Middle cerebellar peduncle Pons Inferior cerebellar peduncle Medulla ablongata

8. Peduncles of the cerebellum

9. Vermis Hemisphere Parts of the cerebellum

10. LOBES OF CEREBELLUM Divisions of lobes Anatomical Flocculonodular lobe Anterior lobe Posterior lobe Anterior lobe Posterior lobe Flocculonodular lobe Inferior surface Superior surface Anterior lobe Posterior lobe

11. Functional(Evolutionary) Paleocerebellum Neocerebellum Archicerebellum Division of lobes…..contd .

12. Archi -cerebellum posterior lobe ( Vestibular part) • It is formed of the flocculo -nodular lobe + associated fastigial nuclei , lying on inf. Surface in front of postero -lateral fissure. • Embryologically , it is the oldest part of cerebellum. • It receives afferent Fibres . From vestibular apparatus of internal ear Via vestibulo-cerebellar tracts. • It is concerned with equlibrium Neocerebellum Archicerebellum Paleocerebellum

13. It has connections with vestibular & reticular nuclei of brain stem through the inferior cerebellar peduncle. Afferent vestibular Fibres . Pass from vestibular nuclei in pons & medulla to the cortex of ipsilateral flocculo -nodular lobe. Efferent cortical ( purkinje cell) Fibres . Project to fastigial nucleus, which projects to vestibular nuclei & reticular formation. It affects the L.M.system bilaterally via descending vestibulo -spinal & reticulo -spinal tracts. Archicerebellum …….contd .

14. Paleo -cerebellum (spinal part) : • it is formed of midline vermis + surrounding paravermis + globose & emboliform nuclei. • It receives afferent proprio-ceptive impulses from Ms.& tendons Via spino-cerebellar tracts (dorsal & ventral) mainly. • it sends efferents to red nucleus of midbrain. • it is concerned with muscle tone Paleocerebellum

15. It is concerned with muscle tone & posture. . Afferents spinal Fibres consist of dorsal & ventral spino-cerebellar tract from muscle, joint & cutaneous receptors to enter the cortex of ipsilateral vermis & para vermis Via inferior & superior cerebellar peduncles . Efferents cortical fibres pass to globose & emboliform nuclei, then Via sup. C. peduncle to contra-lateral red nucleus of midbrain to give rise descending rubro -spinal tract.

16. Neo-cerebellum (cerebral part) • It is the remaining largest part of cerebellum. • It includes the most 2-cerebellar hemispheres + dendate nuclei . • It receives afferent impulses from the cerebral cortex+pons Via cerebro-ponto - cerebellar pathway. • it sends efferents to Ventro lateral nucleus of thalamus. •it controls voluntary movements (muscle coordination). Neocerebellum

17. It is concerned with muscular coordination. It receives afferents from cerebral cortex involved in planning of movement- to pontine nuclei ,cross to opposite side Via middle Cerebellar peduncle to end in lateral parts of cerebellum ( cerebro-ponto-cerebellar tract). Neo- cerebellar efferents project to dendate nucleus ,which in turn projects to contra-lateral red nucleus & ventral lateral nucleus of thalamus ,then to motor cortex of frontal lobe, giving rise descending cortico -spinal & cortico -bulbar pathways. Efferents of dentate nucleus form a major part of superior C. peduncle.

18. Other types of Divisions Afferent regions — Spinocerebellum — Pontocerebellum Efferent regions — Vestibulocerebellum — Lateral Hemisphere

19. Ontogenic development Archicerebellum Paleocerebllum Neocerebellum Classification by Afferent Connection Vestibulocerebellum Spinocerebellum Pontocerebellum Classification by Efferent Connection Vermis Paravermal Region Cerebellar Hemisphere Archicerebellum Nodulus Archicerebellum flocculus Palaeocerebellum Neocerebellum Spinocerebellum Pontocerebellum Vestibulocerebellum Classification by phylogenetic Summary of classification

20. Cortex Medulla Structure of the cerebellum

21. Vermis Hemisphere Nodulus Flocculus Subdivision of Flocculonodular lobe Vermis Hemisphere Lingula Central lobule Ala of the central lobule Subdivision of Anterior lobe Subdivision of lobes Flocculus Nodulus Lingula Central lobue l Ala of central lobule

22. Vermis Hemisphere Declive Simple lobule Postcentral fissure Vermis Hemisphere Folium Superior semilunar lobule Vermis Hemisphere Tuber Inferior semilunar lobule Gracile lobule Horizontal fissure Posterior lobe Declive Simple lobule folium Superior semilunar lobule Tuber Inferior seminular lobule uvula

23. Vermis Hemisphere Pyramid Biventral lobule Uvula Tonsil

24. Ant lobe Post lobe Inferior surface Ant lobe Post lobe Superior surface

25. Structure Cerbellum consists of outer layer of grey matter known as cortex and inner layer of white matter known as medulla. The medullary core is composed of incoming and outgoing fibres projecting to and from the cerebellar cortex. Medullary core also contain the nucleuses of the cerebellum which are four in number.

26. Cortex Medulla Structure of cerebellum

27. Structure of cerebellar ……contd. Cerebellar Cortex Molecular Layer Purkinje Cell Layer Granular Layer Corpus Medullare ( Medullary Center) Deep Cerebellar Nuclei Fastigial Nuclei Nucleus Interpositus Emboliform Nucleus Globose Nucleus Dentate Nucleus

28. CEREBELLUM cortex Cerebellar Cortex I. Molecular Layer Stellate Cell --- taurine (inhibitory) afferent: parallel fiber efferent: Purkinje cell dendrite Basket Cell ---- GABA (inhibitory) afferent: parallel fiber efferent: Purkinje cell soma Parallel Fiber granule cell axon Purkinje Cell Dendrite

29. Cerebellum layers……contd. II. Purkinje Cell Layer Purkinje Cell -- 15,000,000 in number -- GABA (inhibitory) afferent: parallel fiber climbing fiber stellate cell basket cell efferent: deep cortical nuclei Bergman’s glial cell

30. Purkinje cells flaskshaped cell, single layered Dendrites Molecular layer - profuse branching - dendritic spines Axon - synapse with deep cerebellar nucleus - basket & stellate cells - vestibular nuclei

31. Cerebellum layers……..contd. III. Granular Layer Granular Cell -- 50,000,000,000 in number -- glutamic acid (excitatory) afferent: mossy fiber efferent: Purkinje cell axon basket cell, stellate cell Golgi cell Golgi Cell -- GABA (inhibitory) afferent: parallel fiber, mossy fiber rosette efferent: granule cell dendrite

32. Climbing fibres - from inferior olivary complex - direct action on individual Purkinje cell - powerful , sharply localised - Basket cells, stellate cells, Golgi cells act as inhibitory interneurons . Mossy fibres -from spinal cord / brain stem centres -indirect action on Purkinje cells via granule cells -diffuse ( thousands of Punkinje cells may be excited )

33. White matter of the cerebellum Consists of three types of nerve fibres in the white matter Axons of purkinje cells The only axons to leave cerebellar cortex to end in deep cerebellar nuclei specially dendate nucleus. Mossy fibres They end in the granular layer. Climbing fibres They end in the molecular layer

34. The internal circuity of cerebellum Donot leave the cerebellum,interconnect different regions of cerebellum. Some connect the same side. Some connect the two cerebellar hemisphere The cerebellar efferent via middle cerebellar peduncle(MCP) and inferior cerebellar peduncle (ICP) The cerebellar afferent via superior cerebellar peduncle(SCP) and from fastigial from inferior cerebellar peduncle(ICP) White matter of cerebellum

35. Afferent pathways to cerebellar cortex excite Purkinje cells . Basket, stellate and Golgi cells regulate Purkinje cell activity Efferent pathways from the cerebellar cortex originate from Purkinje cells - Intrinsic pathway

36. Intrinsic pathway

37. Cerebellar AFFERENT pathway From cerebral cortex cortico-ponto-cerebellar fibres cerebro-olivo-cerebellar fibres cerebro - reticulo - cerebellar fibres From spinal cord anterior spinocerebellar tract posterior spinocerebellar tract cuneocerebellar tract From vestibular nucleus vestibulocerebellar tract [ flocculonodular lobe ] From other areas red nucleus, tectum

38. Afferent pathway origin Destination via Corticopontocerebellar Frontal,parietal , temporal, occipital Pontine nuclei & mossy fibres to cerebellar cortex Cerebroolivocerebellar INF olivary N & climb fibres to cerebellar cortex Cerebroreticulocerebellar Sensorimotor areas Reticular formation Ant spinocerebellar Muscle spindles,tendons , joints Mossy fibres to cerebellar cortex Post spinocerebellar Cuneocerebellar Vestibular nerve Utricle, saccule,semicircular canals Mossy fibres to cortex of FN node others Red nuc , tectum cerebellar cortex

39. Cerebellar EFFERENT pathways Axons of Purkinje cells synapse with the cerebellar nuclei. Axons of the neurones form the efferent pathways Connect with Red nucleus Thalamus Vestibular nuclei Reticular formation

40. Histological structure of cerebellum

41. Molecular layer Purkinje layer Granular layer Histology of the cerebellum….. contd

42. Cerebellar cortex…..contd. Synaptic Glomerulus Afferent terminals on granular layer  Mossy Fiber Rosette -- afferent fibers except inferior olivary input -- 2/3 of medullary center  Granular Cell Dendrite -- main afferent input  Golgi Cell Axon -- synapse on granule cell dendrite -- GABA (inhibitory) - Surrounded by Astrocyte Foot Process

43. Cerebellar structure……Deep nuclei 1. fastigial nucleus 2. globose nucleus 3. emboliform nucleus 4. dentate nucleus

44. Dentate nucleus Emboliform nucleus Globose nucleus Fastigial nucleus Nucleus interpositus Deep nucleuses of cerebellum

45. Fibres entering and leaving through cerebellar peduncles Superior cerebellar peduncle Fibres entering the cerebellum 1. Ventral spino-cerebellar tract 2. Rostral spino-cerebellar tract 3. Tecto-cerebellar fibres 4. Rubro-cerebellar fibres 5. Trigemino-cerebellar fibres 6. Hypothalamo-cerebellar fibres 7. Coerulo-cerebellar fibr es Fibres leaving the cerebellum 1. Cerebello-rubral fibres 2. Cerebello -thalamic fibres 3. Cerebello -reticular fibres 4. Cerebello-olivary fibres 5. Cerebello -nuclear fibres 6. Some fibres to hypothalamus and thalamus Superior cerebellar peduncle

46. Middle cerebellar peduncle Pontocerebellar fibres Inferior cerebellar peduncle Fibres entering cerebellum 1. Posterior spino cerebellar tract 2. Cuneo- cerebellar tract 3. Olivo-cerebellar fibres 4. Reticulo-cerebellar fibres 5. Vestibulo-cerebellar fibres 6. Anterior external arcuate fibres 7. Fibres of striae medullaries 8. Trigemino-cerebellar fibres Fibres Leaving the cerebellum 1. Cerebello-olivary fibres 2. Cerebello -vestibular fibres 3. Cerebello spinal and cerebello reticular fibres Middle cerebellar peduncle Inferior cerebellar peduncle

47. Classification of cerebellum Classification by phylogenetic and Ontogenic development Archicerebellum Paleocerebllum Neocerebellum Classification by Afferent Connection Vestibulocerebellum Spinocerebellum Pontocerebellum Classification by Efferent Connection Vermis Paravermal Region Cerebellar Hemisphere Archicerebellum Nodulus Archicerebellum flocculus Palaeocerebellum Neocerebellum Spinocerebellum Pontocerebellum Vestibulocerebellum

48. CT SCAN OF BRAIN WITH CEREBELLUM

49. MRI OF BRAIN WITH CEREBELLUM

50.  Maintenance of Equilibrium - balance, posture, eye movement  Coordination of half-automatic movement of walking and posture maintenace - posture, gait  Adjustment of Muscle Tone  Motor Leaning – Motor Skills  Cognitive Function Functions of cerebellum

51. Balance

52. Motor skills

53. Ataxia: incoordination of movement - decomposition of movement - dysmetria , past-pointing - dysdiadochokinesia - rebound phenomenon of Holmes - gait ataxia, truncal ataxia, titubation Intention Tremor Hypotonia , Nystagmus Archicerebellar Lesion: medulloblastoma Paleocerebellar Lesion : gait disturbance Neocerebellar Lesion : hypotonia , ataxia, tremor Syndromes

54. Cerebellar Ataxia Ataxic gait and position: Left cerebellar tumor a. Sways to the right in standing position b. Steady on the right leg c. Unsteady on the left leg d. ataxic gait

55. Cerebellar Medulloblastoma Cerebellar tumors on vermis - Truncal Ataxia - Frequent Falling The child in this picture: - would not try to stand unsupported - would not let go of the bed rail if she was stood on the floor.

56. Are usually vascular, may be traumatic or tumour . Manifestations of unilateral cerebellar lesions : 1-ipsilateral incoordination of (U.L) arm = intention tremors : it is a terminal tremors at the end of movement as in touching nose or button the shirt. 2-Or ipsilateral cerebellar ataxia affects (L.L.) leg , causing wide-based unsteady gait. Manifestations of bilateral cerebellar lesions (caused by alcoholic intoxication, hypothyrodism , cerebellar degeneration & multiple sclerosis) 1-dysarthria : slowness & slurring of speech. 2-Incoordination of both arms.= intention tremors. 3-Cerebellar ataxia : intermittent jerky movements or staggering ,wide-based, unsteady gait 4-Nystagmus : is a very common feature of multiple sclerosis. It is due to impairment coordination of eye movements /so, incoordination of eye movements occurs and eyes exhibit a to-and-fro motion. Combination of nystagmus + dysarthria + intension tremors constitutes Charcot’triad , which is highly diagnostic of the disease. Cerebellar lesions

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