Cerebellum

Introduction

Anatomy

Circuits

Functions

Lesions and examination

"Little brain":

  • 10% entire brain
  • 50% of all neurons in the entire CNS
  • Contains deep cerebellar nuclei
  • Attached to brainstem by cerebellar peduncles

Functions:

  • "Error correction" = motor learning
    • Integrates executive commands with sensory feedback regarding ext and int env
    • Learns new behavioral programs
    • Output directed by UMN
  • Organ of agility
    • Motor and cognitive
    • Spatial accuracy
    • Temporal coordination
    • Balance

Location:

  • Posterior fossa
  • Dorsal to pons and medulla
  • Separated by aqueduct of Sylvius and 4th ventricle

Functional anatomy

Peduncles

Deep nuclei

Cerebellar anatomy

  • 2 basic regions:
    • Midline structures = Vermis
    • Cerebellar hemispheres
  • Lobes
    • Flocculonodular
    • Anterior lobe (small)
    • Posterior lobe (large)
  • Spinocerebellum:
    • Proprioceptive information, visual + audittory (from muscle spindles)
  • Cerebrocerebellum (=neocerebellum):
    • Processing info from cortex
    • Include dentate nucleus
    • Fine and skilled motor coordination
  • Vestibulocerebellum (=floculonodular/archicerebellum)
    • Receives/sends input to vestibular nuclei
    • Relative to vestibular function and equilibrium
    • Includes Fastigial nucleus and project to gaze of brainstem

Functional division of spinocerebellum

  • Axial muscle = in the middle along Vermis
  • Distal extremities = into paramedian strip
  • Superior cerebellar peduncle
    • Efferent pathway (mainly)
    • Superior brachium conjunctivum
  • Inferior cerebellar peduncle
    • Afferent and Efferent pathways
    • 2 parts: Restiform and Justarestiform
  • Middle cerebellar peduncle
    • Afferent pathway
    • Largest
  • Dentate
  • Fastigial
  • Interposed:
    • Emboliform
    • Globose

Deep nuclei's input:

  • Cerebrocerebellum = Voluntary mvt
  • Medial region of spinocerebellum (vermis) and small from flocculonodular lobe
  • Lateral aspect of the spinocerebellum = Active during mvt

Local

Output

Input

Feedback

Learning

Executive

Sans titre

Signal relayed from cerebral cortex in frontal and parietal lobes via pontine nuclei

Signals from proprioceptive systems:

  • Conveys sensory information about ongoing behavior

Signals derived from inferior olivary nucleus of the medulla = facilitates adaptation (error correction)

Remember :Cerebellum represent the ipsilateral side of the body and so the contralateral cortex