Physiology of Cerebellum

1. CEREBELLUM

2. OBJECTIVES
■ Physiological Anatomy
■ Neural circuits & neuronal activity
■ Connections
■ Functions
■ Applied physiology.

3. Cerebellum.
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■ Largest part of hind brain.
■ Called “silent area.”
■ Weight- 150 gms.

4. Physiological anatomy.
■ External features .
■ Anatomical parts.
■ Anatomical divisions.
■ Phylogenetically divisions.
■ Functional divisions.
■ Histological structure.
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5. External features
■ Surfaces .
■ Folia.- transverse
folds
■ Fissures.
■ Primary
■ Horizontal
■ Posterolateral.
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6. Anatomical parts
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■ Parts of vermis.
■ Lingula
■ Central lobule
■ Culmen
■ Declive
■ Folium
■ Tuber
■ Pyramis
■ Uvula
■ Nodule.
■
■
■
■
■
■
■
■
■
■ Parts of hemisphere.
No lateral projection. Alae
Anterior quadrangular lobule
Posterior quadrangular
lobule
Superior semilunar lobule
Inferior semilunar lobule.
Biventral lobule
Tonsil
Flocculus.

7. Anatomical divisions
■ Anterior lobe.
■ Posterior lobe.
■ Flocculonodular lobe..
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8. Phylogenetically
divisions
■ Archicerebellum
■ Floculonodular lobe
■ Lingula
■ Paleocerebellum
■ Anterior lobe except – lingula
■ Posterior lobe – pyramis, uvula & paraflocculus.
■ Neocerebellum.
■ Whole posterior lobe except –pyramis & uvula.
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10. Functional divisions.
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■ Vestibulocerebellum.
■ Consists of
Floculonodular lobe
■ Vestibular connections
■ N. fastigeal – effector N.
■ Control body posture &
equilibrium.
■ Spinocerebellum.
■ Consists of
Paleocerebellum.
■ N Interpositus. – effector N.
■ Postural reflexes.
■ Corticocerebellum.
■ Central cerebellum
■ Dentate N.- effector
nucleus.
■ Smooth performance.

11. Functional divisions.
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12. Histological structure.
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■ Cerebellar cortex.
■ Molecular layer.
■ Purkinje cell layer.
■ Granule cell layer.
■ White matter.
■ Projection fibres.
■ Association fibres.
■ Commissural fibres.
■ Deep cerebellar nuclei.
■ Dentate nucleus.
■ Emboliform nucleus.
■ Globossus nucleus.
■ Fastigeal nucleus.

13. Histological structure.
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14. Cerebellar cortex.
■ Molecular layer.
■ Stellate cells
■ Basket cells.
■ Purkinje cell layer.
■ Granule cell layer.
■ Granule cells
■ Golgi cells.
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15. Cerebellar cortex.
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16. Sensory inputs.
■ Climbing fibres
■ Inferior olivary nucleus
■ Cerebellum.
( purkinje cells)
■ Mossy fibres.
■ Spino, vestibulo,
reticulo, cuneo &
corticoponto
■ Cerebellum
(Glomerulus)
Olivocerebellar tract.
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17. Sensory inputs.
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20. White matter.
■ Projection fibres. ■ Association fibres.
■ Commissural fibres.
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21. Deep Cerebellar Nuclei.
■ Dentate nucleus.
■ Emboliform
nucleus.
■ Globossus nucleus.
■ Fastigeal nucleus.
Near roof of IV
ventricle.
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23. Neural circuits & neuronal
activity.
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■ Afferents of cerebellar cortex.
■ Climbing Fibres.
■ Mossy Fibres.
■ Neuronal activity of deep cerebellar circuits
■ Feed forward inhibition of purkinje cells.
■ Feed forward inhibition of Granule cells.
■ Feed back inhibition of Granule cells.
■ The reverberating circuits.
■ Neuronal activity of deep cerebellar nuclei.

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26. Afferents of cerebellar cortex.
■ Climbing Fibres. ■ Mossy Fibres.
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27. Neuronal activity of deep
cerebellar circuits
■ Feed forward inhibition of Purkinje cells.
■ Mossy fibres Granule cells
■ Purkinje cells. Basket cells.
■Feed forward inhibition of Granule cells. Mossy
fibres Granule cells.
Golgi cells
■ Feed back inhibition of Granule cells.
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28. Neuronal activity of deep
cerebellar neuclei.
Cerebral cortex
Thalamus
motor
pathway.
spinal cord.
brainstem nuclei.
Deep cerebellar nuclei.
Climbing fibres, mossy fibres.
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29. Connections of cerebellum.
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■ Cerebellar Peduncles..
■ Inferior
■ Afferents
▪ Dorsospinocerebellar.
▪ External arcuate
fibres.
▪ Vestibulocerebellar
tract.
▪ Oliocerebellar tract.
▪ Reticulocerebellar
tract.
■ Middle.
■ Afferents. – cerebro-
pontine – cerebellar.
■ Superior
■
■ Afferent –
▪ Tectocerebellar
▪ Ventral
spinocerebellar
Efferent –
▪ Dentorubral
▪ Dentothalamic
▪ Mid-brain.

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31. Afferent connections
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■ Dorsal spinocerebellar tract. (external)
■ Ventral spinocerebellar tract. (Internal)
■ Cuneocerebellar tract.
From accessory cuneate N.
■ Olivocerebellar tract.
From brainstem, SC, cortex

32. Afferent connections
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■ Cortico-ponto-cerebellar tract.
■ Tectocerebellar tract.
From superior colliculi (visual impulses)&
inferior colliculi (auditory impulses)of
tectum of mid brain.
■ Vestibulocerebellar tract. (position &
movement of head)
■ Rubrocerebellar tract. ( from motor cortex )
■ Reticulocerebellar tract.

33. Afferent connections
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34. Localization of sensory
impulses to cerebellum.
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35. Efferents connections.
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■ Dento-rubro-thalamo-
cortical pathway.
■ Cerebello-thalamic-
cortical pathway.
■ Cerebelloreticular
pathway.
■ Cerebellovestibular
fibres.
■ Cerebello-olivary
fibres.
■ Oculomotor nerve &
tectum.

36. Efferent connections.
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38. Functions of cerebellum.
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■ Control of body posture & equilibrium.
■ Control of muscle tone & stretch reflex.
■ Control of voluntary movements.

39. Control of body posture &
equilibrium.
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40. Control of muscle tone &
stretch reflex.
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41. Control of voluntary movements.
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42. Mechanism of action.
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■ Comparator function.
■ Damping action.
■ Timing & programming the movements.
■ Control of ballistic movements.
■ Servomechanism.

43. Comparator function.
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44. Other functions of cerebellum.
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■ Autonomic system (through Hypothalamus &
reticular formation.)
■ Ascending sensory pathway. (through
reticular formation & thalamus)
■ Eyeball movements. ( through vestibular
nuclei)

45. Cerebellar lesions.
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■ Common causes.
■ Signs of cerebellar dysfunction.
■ Tests .

46. Common causes.
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■ Vascular occlusions (thrombosis)
■ Tumor
■ Injuries.

47. Signs of cerebellar dysfunction.
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■ Tone & posture disturbance
■ Atonia or hypotonia
■ Attitude changes.
■ Rotation of face to opposite side
■ Lowering of shoulder.
■ Outward rotation & abduction of leg.
■ Deviation movements.
■ Effect on deep reflexes. (weak & pendular)

48. Signs of cerebellar dysfunction.
s
■ Equilibrium disturbance. (drunken gait)
■ Movements disturbance.
■ Ataxia
■ Intention tremor
■ Nystagmus.
■ Dysarthria.
■ Astasia.
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49. Clinical tests of cerebellar
dysfunction.
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■ Upper limb
■ Finger nose test
■ Diadokokinesia.
■ Rebound phenomenon.
■ Past pointing.
■ Lower limb.
■ Rombergs test.
■ Tandem gait.

50. Tests .
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51. Thank
You