Cerebellum Worksheet - Lecture 9 Flashcards
where is the cerebellum located
dorsally to the pons and medulla
in the posterior cranial fossa
what separates the CB from the occipital and temporal lobes
tentorium cerebelli
what would happen if the Cb was compressed or pushed downward
add pressure to the pons, medulla and SC
where does the cerebellum receive its blood supply
vertebrobasilar system
–> posterior inferior cerebral artery (PICA)
–> anterior inferior cerebral artery (AICA)
–> superior cerebral artery (SCA)
what are the 3 ways to divide the Cb
zones
lobes
fxn
zones
vermal (median) zone
paravermal (intermediate) zone
hemispheric (lateral) zone
lobes
anterior
posterior
flocculonodular
how are the lobes connected to the rest of the brain
3 dense fiber bundles
–> peduncles
fxn
vestibulocerebellum
spinocerebellum
cerebrocerebellum
vestibulocerebellum role
maintenance of balance
control of eye movements
spinecerebellum role
regulation of muscle tone
coordination of skilled voluntary movement
cerebrocerebellum role
planning and modulation of voluntary activity
storage of procedural memories
three layers of the Cb cortex
molecular (outermost)
purkinje (middle layer)
granular (innermost)
molecular layer
contains 2 primary interneurons
–>inhibitory in nature
both help to communicate with purkinje cell dendrites via GABAergic synapses
2 primary interneurons of the molecular layer
stellate cells
basket cells
purkinje layer contains
cells with some of the largest neurons in the human brain
how are purkinje fibers arranged
stacked one in front of the other
domino like
purkinje cells communicate
with deep cerebellar nuclei
granular layer
mossy fibers enter the granular layer from the pontine nuclei
what are formed in the granular layer
excitatory synapses with granule cells and cells of the deep cerebellar nuclei
how many synapses are created –> granular layer
hundred to thousands w/ purkinje cell dendrites
deep cerebellar nuclei
fastigial, glubose, emboliform, dentate
involved in influencing the descending motor pathways and the motor neurons of the brain stem and SC
what are the deep cerebellar nuclei the main source of
cerebellar output
receive collaterals of cerebellar afferents and purkinje cell axon terminals from the overlying cerebellar cortex
fastigal nucleus location
roof of the 4th ventricle
what does the fastigal nucleus receive
fibers arising from the vestibulocerebellum and first order collaterals form the vestibular apparatus
where do outputs from the fastigal nucleus go
lateral and inferior vestibular nuclei
influence the vestibulospinal tracts
what does the fastigal nucleus play a larger role in
balance
eye fxn
vestibulospinal reflex
globuse and emboliform nuclei
together referred to as the interposed nuclei
afferents to interposed nuclei
purkinje cell terminals arising from the spinocerebellum
where do the interpose nuclei project to
red nucleus
rubrospinal tract
what do the interpose nuclei project via
ventral lateral nucleus of thalamus
lateral corticospinal tract
denate nucleus
largest of the cerebellar nuclei
tooth shaped
where does the denate nucleus receive inputs from
collaterals of pontocerebellar afferents
purkinje cell terminals originating from the cerebrocerebellar
where does output from the denate nucleus go
premotor and primary motor cortexes via ventral lateral nucleus of the thalamus
what do the outputs of the denate nucleus do
influence upcoming motor activity thats about to occur
final determinant of movement
what else does the denate nucleus participate in
vestibulo-oculomotor pathways
what does the Cb receive while initiating movement
efference copy of movement
from the frontal and parietal cerebral motor cortices
via the relay pons
what does the efference copy of movement give the Cb
info to compare with the motion feedback it gets from the body
what is the Cb enabled to do –> movement
compare performed movement to the desired movement
what can the Cb compare
current movement with the movement performed in the past
in order to make changes and modify the movements to be most effective
what does the Cb allow
correction of movement as it unfolds
proprioceptive feedback of the Cb
tells the Cb how the body is moving
how does the body tell the Cb how the body is moving
SC relays the proprioceptive info of ongoing movement and posture for to immense # of muscle spindles and other mechanoreceptors throughout the body
what does the vestibular nuclei do during proprioceptive feedback
sends info on angular and linear acceleration from labyrinth in the ear
what does the inferior olive do during proprioceptive feedback
active role in developing memory of the Cb
in order for us to master new complex movements
where can lesions occur
central, anterior and posterior lobes of Cb
including the vermin (spinocerebellum)
what do lesions result in
LE dyscoordination and/or deficits in LE equilibrium response
