ANATOMY CEREBELLUM functinal classification.pptx

Cerebellum and connection

1. CEREBELLUM

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 Deepest fissure is primary fissure which divides cerebellum in to anterior and posterior parts

4. CEREBELLAR HOMUNCULUS

5. ANATOMICAL CLASSIFICATION

6. FUNCTIONAL CLASSIFICATION VESTIBULOCEREBELLUM NEOCEREBELLUM SPINOCEREBELLUM

7. PHYLOGENETIC CLASSIFICATION ARCHICEREBELLUM ( VESTIBULOCEREBELLUM) PALEOCEREBELLUM (ANTEROR LOBE) NEOCEREBELLUM(HEMISPHERE)

8. Cerebral Nuclei Dentate Emboliform Festigial Globose

9. 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

10. Cerebellar peduncles Cerebellar peduncles connect the cerebellum to the brain stem. Superior cerebellar peduncle is a paired structure of white matter that connects the cerebellum to the midbrain. Inferior cerebellar peduncle is a thick rope- like strand that occupies the upper part of the posterior district of the medulla oblongata. Middle cerebellar peduncles connect the cerebellum to the pons and are composed entirely of centripetal fibers.

11. Cerebellar Cortex Molecular Layer Purkinje Cell Layer Granular Layer

12. HISTOLOGY

13. CEREBELLUM CORTEX Molecular Layer Stellate Cell:- taurine (inhibitory) afferent: parallel fiber efferent: Purkinje cell dendrite Basket Cell :- GABA (gamma- aminobutyric acid)(inhibitory) (Inhibit or reduce the activity of the neurons or nerve cells) afferent: parallel fiber efferent: Purkinje cell soma Parallel Fiber granule cell axon Purkinje Cell Dendrite

14. 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

15. Purkinje cells flaskshaped cell, single layered Dendrites – Molecular layer – Profuse branching – Dendritic spines Axon synapse with deep cerebellar nucleus basket & stellate cells vestibular nuclei

16. 3.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 GABA (inhibitory) afferent: parallel fiber, mossy fiber rosette efferent: granule cell dendrite

17. 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 )

18. 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

19. 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

20. 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 -

21. 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

22. Afferent pathway origin Destination via Corticopontocerebellar Frontal, parietal, temporal, occipital Pontine nuclei & mossy fibres to cerebellar cortex Cerebroolivocerebellar 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

23. 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

24. Fibres entering and leaving through cerebellar peduncles Superior cerebellar peduncle Fibres entering the cerebellum Ventral spino- cerebellar tract Rostral spino- cerebellar tract Tecto- cerebellar fibres Rubro- cerebellar fibres Trigemino-cerebellar fibres Hypothalamo-cerebellar fibres Coerulo- cerebellar fibres Fibres leaving the cerebellum Cerebello- rubral fibres Cerebello- thalamic fibres Cerebello-reticular fibres Cerebello-olivary fibres Cerebello- nuclear fibres Some fibres to hypothalamus and thalamus Superior cerebellar pedun

25. Middle cerebellar peduncle Pontocerebellar fibres Inferior cerebellar peduncle A. Fibres entering cerebellum Posterior spino cerebellar tract Cuneo- cerebellar tract Olivo- cerebellar fibres Reticulo- cerebellar fibres Vestibulo- cerebellar fibres Anterior external arcuate fibres Fibres of striae medullaries Trigemino-cerebellar fibres B. Fibres Leaving the cerebellum Cerebello-olivary fibres Cerebello- vestibular fibres Cerebello spinal and cerebello reticular fibres Middle cerebellar pedunc Inferior cerebellar peduncle

26. BLOOD SUPPLY

27. Functions Regulates posture and postural activities Muscular co- ordination and balance Detection and correction of motor output from cortex Controls timing of motor activities Maintenance of body posture,equlibrium and eye movements. cerebellum may also have non- motor functions such as cognition (acquisition of knowledge) and language processing.

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