Motor Modulation - Cerebellum Flashcards
loss of coordination will produce what?
ataxia
what are the functions of the cerebellum?
- coordination of timing between muscle groups to produce fluid movements
- ongoing adjustments of posture and balance
- correcting or avoiding movement errors
- motor learning
when are cerebellar circuits active?
before a movement or while a movement is going on
the cerebellum has two hemispheres connected by what?
vermis
what are the three lobes of the cerebellum?
- anterior lobe
- posterior lobe
- flocculonodular lobe
what are the white matter tracts of the cerebellum?
- middle cerebellar peduncles
- superior cerebellar peduncles
- inferior cerebellar peduncles
where is the grey matter located in the cerebellum?
- on the external cerebellar cortex arranged in long parallel folds called folia
- in the white matter as deep nuclei
what are the four deep nuclei of the cerebellum?
- dentate
- emboliform
- globose
- fastigial
*emboliform and globose are know collectively as “interposed nuclei”
what fibers do the white matter tracts contain?
- inferior: both incoming and outgoing
- middle: only incoming
- superior: both incoming and outgoing
what are the three main arteries that feed the cerebellum?
- superior cerebellar
- anterior inferior cerebellar
- posterior inferior cerebellar
what does the superior cerebellar artery branch from and what does it supply?
- branches from rostral basilar artery
- supplies the superior portion of the cerebellum, deep cerebellar nuclei and superior cerebellar peduncle
what does the anterior inferior cerebellar artery branch from and what does it supply?
- branches from the caudal basilar artery
- supplies the anterior strip of the cerebellum including superior vermis and middle cerebellar peduncle
what does the posterior inferior cerebellar artery branch from and what does it supply?
- branches from the vertebral artery
- supplies the inferior cerebellum including the nodulus
what is the location of the spinocerebellum and what is its nuclei?
- vermis and paravermis
- interposed nuclei and fastigial nuclei
what is the location of the cerebrocerebellum and what is its nuclei?
- lateral hemispheres
- dentate nuclei
what is the location of the vestibulocerebellum and what is its nuclei?
- flocculonodular lobe
- fastigial nucleus
what does the spinocerebellum function in?
error correction: detects difference between motor plan and actual movement
where does the spinocerebellum receive projections from?
- proprioceptors (muscle spindles/golgi tendons)
- inferior olive
cortical neurons of the spinocerebellum synapse with the dorsal column nucleus and output to what two motor tracts?
- UMN of the medial motor tracts (vestibular nuclei and reticular formation)
- UMN of lateral corticospinal tract via the ventral lateral nucleus of the thalamus
what does the vermis coordinate movements for?
central body
what does the paravermis coordinate movement for?
distal muscles
cerebellar lesions restricted to the medial cerebellum have what effects?
- bilateral loss of coordination of proximal muscles effecting balance posture and gait
what is located in the medial cerebellum?
vermis and or fastigial nucleus
cerebellar lesion in the lateral/intermediate zone can have what effect?
ipsilateral movement deficits
- loss of coordination (appendicular ataxia)
- inaccuracy in range and direction of movement (dysmetria)
- trouble with patterned movement (dysdiadochokinesia)
what does the vestibulocerebellum function in?
- corrections in stability and balance (continuous and anticipatory)
- vestibular ocular reflex and smooth pursuit
where does the vestibulocerebellum receive projections from?
- vestibular nuclei and vestibular ganglia
- inferior olivary nucleus
where does the vestibulocerebellum output to?
- vestibular nuclei
- reticular formation ‘
- bypasses the DCN
what does the cerebrocerebellum function in?
- motor learning
- calculating movement trajectories
where does the cerebrocerebellum receive projections from?
- neurons in the base of the pons (pontine nuclei)
- inferior olivary nucleus
where does the cerebrocerebellum output to?
UMNs of lateral movement pathways vis the ventral posterior lateral nucleus of the thalamus
where do the incoming fibers synapse in the cerebellum?
- on neurons of the deep cerebellar nuclei
- on neurons called purkinje cells in the cerebral cortex
what do the deep cerebellar nuclei control?
- excitatory input that stimulates these neurons to fire
- error correction signals out to the CNS (deep excitatory loop)
what do the Purkinje Fibers provide?
modularly inhibition to the deep cerebellar nucleus to adjust the outgoing signal
where do mossy fibers originate from?
spinal cord, pontine nuclei and vestibular nuclei
where do mossy fibers synpase?
on the deep cerebellar nucleus or on granule cells of the cortex
what happens if a mossy fiber synapses with a granular cell?
granule cells send axons towards Purkinje cell dendrites and the axons then bifurcate into a T shape called a parallel fiber
axons from the inferior olive enter the cerebellum as what fibers?
climbing
