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
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