FNS 25 Cerebellum

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FNS 25 Cerebellum
2011-03-09 21:03:23
USUHS Cerebellum

FNS 25 Cerebellum
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  1. Motor activities of the cerebellum (3)
    • 1. Ipsilateral movement planning/coordination
    • 2. Maintaining posture and balance
    • 3. Controlling eye movements
  2. Cerebellar Cortex Layers
    Granule, Purkinje and molecular layers
  3. What is the Medullary Substance?
    White matter - axons to and from the cerebellar cortex
  4. What are the Intrinsic Nuclei?
    Four pairs of deep cerebellar nuclea in the medullary substance

    • Fastigial
    • Globose
    • Emboliform
    • Dentate
  5. ICP, MCP, SCP Paths
    ICP: medulla to cerebellum

    MCP: pons to cerebellum

    SCP: midbrain to cerebellum
  6. Subdivisions of the Cerebellar Cortex
    Vestibulocerebellum (flocculonodular lobe)

    Spinocerebellum (vermis and medial hemispheres)

    Pontocerebellum (lateral hemispheres)
  7. How is sensory information to the Cerebellar Cortex organized?

    • lower limbs - anteriorily
    • upper limbs - posteriorily
    • proximal - medially
    • distal - laterally
  8. Vestibulocerebellar Afferent Fibers (origin, laterality)
    • 1. Primary Afferent Fibers
    • uncrossed from bipolar neurons of vestibular ganglion

    • 2. Secondary Afferent
    • uncrossed from vestibular nuclei
  9. Spinocerebellar Afferent Fibers (origin, laterality, function)
    • 1. PSCT - Posterior Spinocerebellar Tract
    • uncrossed from Dorsal Nuc of Clarke
    • lower limb proprioception

    • 2. CCT - Cuneocerebellar Tract
    • uncrossed from Accessory Cuneate Nuc
    • upper limb proprioception

    • 3. ASCT - Anterior Spinocerebellar Tract
    • double-crossed from spinal intermediate zone
    • Golgi tendon info

    • 4. Spinoreticulo-Cerebellar Pathways
    • uncrossed from lateral reticular nucleus

    • 5. Trigeminocerebellar Fibers
    • uncrossed from CN V sensory nuclei
  10. Pontocerebellar Afferent Fibers
    • crossed from pontine nuclei via MCP
    • serves as communication between cerebral cortex and contralateral pontocerebellum
  11. Olivocerebellar Fibers
    Crossed from Inferior Olivary Complex via ICP

    Terminate as climbing fibers on Purkinje cells in each cerebellar subdivision
  12. Afferent Fiber Types
    Mossy Fibers - synapse on granule cells

    Climbing Fibers - synape on Purkinje cells
  13. Mossy Fibers
    Found in granule cell layers

    Excitatory synapses with dendrites of granule cells and deep cerebellar neurons

    Indirectly stimulate Purkinje Cells

    Used for moment-to-moment coordination
  14. Granule Cells
    Bifurcate and ascent into molecular layers as Parallel Fibers

    Excitatory synapses on Purkinje dendrites and all inhibitory interneurons
  15. Golgi Cells
    Interneurons which inhibit granule cell dendrites within the cerebellar glomeruli
  16. Cerebellar Glomeruli Contains:
    • Granule cell dendrites
    • Mossy fiber axon terminal
    • Golgi cell axon terminal
    • Glial capsule
  17. Purkinje Cell Layer
    • Inhibit deep cerebellar neurons using GABA
    • Only output of cerebellar cortex
  18. Molecular Cell Layer components
    • Climbing Fibers
    • Parallel Fibers
    • Basket Cells
    • Outer Stellate Cells
  19. Climbing Fibers
    • From IOC
    • Excite Purkinje cells and deep cerebella nuclei
    • Fuctions include movement synchronization and motor learning
  20. Basket Cells
    • Excited by parallel fibers
    • Inhibit purkinje cell somata
  21. Outer Stellate Cells
    • Excited by parallel fibers
    • Inhibit Purkinje cell dendrites
  22. Vestibulocerebellar Efferents
    Purkinje cells in Flocculonodular Lobe synapse directly on vestibular nuclei

    Ipsilateral Righting Reflex and Eye Coordination
  23. Spinocerebellum: Vermal Pathway
    • Purkinje cells in the vermis to Fastigial Nuc
    • Ipsilateral axial muscle control for posture/balance
  24. Spinocerebellum: Paravermal Pathway
    • Pukinje cells in paravermis to Globose and Emboliform Nuc
    • Terminate contralaterally in Red Nucleus and thalamus
    • Fine control of distal muslces
  25. Pontocerebellar Effents
    • Purkinje cells in pontocerebellum to Dentate Nuc
    • Cross to Red Nucleus and thalamus
    • Planning of Complex Movements
  26. Nodular lesion
    • Vestibulocerebellum affected
    • symptoms: ataxic gait, head tremor, nystagmus
    • Recumbent improvement
  27. Vermal Spinocerebellar lesion
    • Often alcohoic degeneration
    • Symptoms: truncal ataxia
  28. Hemispheric Lesions
    • Ipsilateral asynergia (disordered movements)
    • Speech disturbances
  29. Dysmetria
    Errors in distance of movements
  30. Intention tremor
    tremor occuring during attempted movement
  31. Dysdiadochokinesis
    Difficulty in repetivite agonistic/antagonistic movements
  32. Dysarthria
    Difficulty in forming spoken words
  33. Scanning Speech
    Irregular fluctuations in volume and rate