Cerebellum Flashcards
Anticipatory feed-forward mechanism
Predict disturbances, using prewired responses modified by experience and improves with practice; responses occur before voluntary movements
Compensatory feed-back mechanism
Occur following loss of balance or body; sway automatic and extremely rapid continuously refined by practice, learning
Sensory input
From visceral, cutaneous and proprioceptive receptors trigger anticipatory and/or compensatory postural adjustments
Proprioceptors involved in postural movements
Important in changes of the neck (rotation, tilting)
Vestibular involved in postural movements
Sense sway via head motion
Visual info involved in postural movements
Input detect motion in visual fields
Hierarchy of command centers
- Cerebellum
- Basal nuclei
- Motor cortex
- Brain stem nuclei
- Spinal cord
Motor Cortex
Voluntary actions of the limbs
Basal ganglia
Loop circuits with cortex compares function, posture, and muscle
Cerebellum
Projects to brainstem and cortex coordination and accuracy of movement
Brainstem nuclei
Vestibular and visual info influencing movement integration of reflexes, postural adjustments, lower motor neurons (nuclei) of several cranial nerves
Spinal cord
Reflexes, spinal tracts, and LMNS
Cerebellum functions
- directly regulates and coordinates execution of specific movements
- coordinates hand and eye movements
- compares movement intention with performance and makes adjustments
- regulates muscle tone
- aides in motor learning
- involved in accuracy in rate, range and direction of movement
Lobes of the cerebellum
- Anterior
- Posterior
- Flocculonodular
Folia
Folds on the surface of the cortex increase surface area
Vestibulocerebellum
- equilibrium/balance
- receives input from semicircular canals, otolithic organs, and superior colliculus; adjusts axial muscles to maintain balance and coordination of eye movements
Spinocerebellum
- adjustment of ongoing movements
- regulation of muscle tone
- compensation for small variations in loads encountered during movement
- smoothing out oscillations (tremors)
- correcting for deviations of intended movements
Cerebrocerebellum
- planning of limb movements
- center of complex feedback circuits modulating motor commands
Hemispheres of the cerebellum are separated into:
- flocculondular lobe: vestibulocerebellum
- vermis: spinocerebellum
- intermediate zone: spinocerebellum
- lateral zone: cerebrocerebellum
Gray matter nuclei anatomy from lateral to medial
- dentate
- emboliform
- globose
- fastigial
Cortical layers of cerebellar cortex
- molecular (superficial)
- purkinje (middle): motor activity
- granular (deepest): relay info from CNS to cerebellar cortex
Inputs to the cerebellum
Input from:
- cerebral cortex
- olive (in medulla) and other brainstem nuclei
- vestibular input
- peripheral proprioception (extrapyramidal spinal cord tracts)
Proprioceptors
Muscles, joints and skin
Proprioception information enters:
Inferior cerebellar peduncle
