1. CEREBELLUM BY DR MANAH CHANDRA CHANGMAI

3. It is also present behind the pons and medulla ablongata,seperated from two structures by the cavity of fourth ventricle.

4. It is covered by tentoriumcerebelli and is connected to brain stem by three cerebellar peduncles.

6. Cerebellar surface is divided by numerous curve transverse fissures giving it a laminated appearance

7. One conspicious fissure “horizontal fissure”extends around dorsolateral border of each hemisphere from middle cerebellar peduncle to vallecula,seperating superior and inferior surfaceHemisphere Superior surface Vermis

9. Primary fissure divides the cerebellum into anterior and posterior lobe.Anterior lobe Primary fissure Posterior lobe

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

11. 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. Fourth ventricle

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

13. Peduncles of the cerebellum

14. Parts of the cerebellum Vermis Hemisphere

16. Anterior lobe

17. Posterior lobePosterior lobe Flocculonodular lobe Superior surface Anterior lobe Posterior lobe

19. Neocerebellum

22. Afferent vestibular Fibres. Pass from vestibular nuclei in pons & medulla to the cortex of ipsilateralflocculo-nodular lobe.

23. Efferent cortical (purkinje cell) Fibres. Project to fastigial nucleus, which projects to vestibular nuclei & reticular formation.

26. . Afferents spinal Fibresconsist of dorsal & ventral spino-cerebellar tract from muscle, joint & cutaneous receptors to enter the cortex of ipsilateralvermis & paravermis Viainferior & superior cerebellar peduncles .

29. 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).

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

32. Structure of the cerebellum Cortex Medulla

33. Subdivision of lobes Subdivision of Flocculonodular lobe Flocculus Nodulus Subdivision of Anterior lobe Lingula Ala of central lobule Central lobue l

34. Posterior lobe Simple lobule Postcentral fissure Declive Superior semilunar lobule folium Horizontal fissure uvula Inferior seminular lobule Tuber

38. Superior surface Ant lobe Post lobe Inferior surface Post lobe Ant lobe

40. The medullary core is composed of incoming and outgoing fibres projecting to and from the cerebellar cortex.

42. 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

43. CEREBELLUMcortex 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

44. 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

46. 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 )

50. Some connect the two cerebellar hemisphere

52. Intrinsic pathway 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 -

53. Intrinsic pathway

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

58. Thalamus

59. Vestibular nuclei

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

62. 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

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

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

65. Fibres entering and leaving through cerebellar peduncles Superior cerebellar peduncle Fibres entering the cerebellum 1. Ventral spino-cerebellar tract 2. Rostralspino-cerebellar tract 3. Tecto-cerebellarfibres 4. Rubro-cerebellarfibres 5. Trigemino-cerebellarfibres 6. Hypothalamo-cerebellarfibres 7. Coerulo-cerebellarfibres Fibres leaving the cerebellum 1. Cerebello-rubralfibres 2. Cerebello-thalamic fibres 3. Cerebello-reticular fibres 4. Cerebello-olivaryfibres 5. Cerebello-nuclear fibres 6. Some fibres to hypothalamus and thalamus Superior cerebellar peduncle

67. 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

68. CT SCAN OF BRAIN WITH CEREBELLUM

69. MRI OF BRAIN WITH CEREBELLUM

70. Functions of cerebellum 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

71. Balance

72. Motor skills

73. Syndromes 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

74. 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

75. CerebellarMedulloblastoma 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.

76. Cerebellar lesions 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 ipsilateralcerebellar 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.

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