CB Flashcards
What are the general functions of the cerebellum?
- regulate equilibrium
- muscle tone and posture
- motor coordination for voluntary mvmts (modifies motor programs in response to environmental changes)
What are the two main fissures of the cerebellum and what do they separate?
posterolateral fissure: separates flocculunodular area from rest of cerebellum
primary fissure: anterior/posterior divisions
What are the deep nuclei of the cerebellum?
dentate
interposed (emboliform, globose)
fastigal
Inferior cerebellar peduncle restiform body
inputs from spinal cord, brainstem
monitors muscle and limb mvmt
ICP juxtarestiform body
interconnects vestibular nuclei and cerebellum
imp for head/eye mvmt
middle cerebellar peduncle
largest, located lateral to pons
gets afferents from: CONTRA basis pontis
relays motor signals from cerebral cortex to cerebellum
superior cerebellar peduncle
mostly EFFERENT fibers
fibers go to red nucleus, thalamus
DECUSSATES
exception to “outflow from SCP” rule: anterior spinocerebellar tract uses SCP to enter cerebellum
How is the cerebellum somatotopically arranged?
fractioned somatotopy
dif parts of body show up multiple dif places
What is the general pattern for how info from the spinal cord and brainstem get into the cerebellum?
- info enters from SC, BS on mossy fibers via ICP and MCP
- synapse in granule layer
- synapse in molecular layer on purkinje cells (PKC)
- synapse in deep cerebellar nuclei
- go to either:
a) red nucleus and thalamus (VL) via SCP
b) vestibular nuclei via ICP
What is the general pattern for how info from the inferior olivary nucleus (ION) gets into the cerebellum?
- info from ION leaves on climbing fibers via ICP
- synapse in molecular layer on PKC
- synapse in deep cerebellar nuclei
- go to either:
a) red nucleus and thalamus (VL) via SCP
b) vestibular nuclei via ICP
What are the three layers of the cerebellar cortex and are they uniform throughout?
yes uniform
from top to bottom:
molecular layer
PKC layer
granule layer
Do climbing fibers from ION synapse in granule layer?
no
What are the excitatory cells of the cerebellar circuit?
mossy fiber
climbing fiber
What are the inhibitory cells of the cerebellar circuit?
stellate
basket
golgi
PKC
What do stellate and basket cells do?
inhibit PKC
What do golgi cells do?
inhibit granule cells
What happens once mossy fibers excite a group of granule cells?
- 100s of PKC are excited via parallel fibers
- PKC inhibit neurons in deep nuclei
- weakly facilitated PKC are edges of activated zone are turned off by stellate, basket cells to focus signal
- golgi cells in granule layer turn off initial signal
Do mossy and climbing fibers send collaterals to deep nuclei before the axon enters the cerebellar cortex?
yes
Where do PKC axons end?
deep nuclei of cerebellum
What CP does the anterior spinocerebellar tract use?
SCP
note: AST crosses midline 2x
What CP does the posterior spinocerebellar tract use?
ICP
What CP does the cuneocerebellar spinocerebellar tract use?
ICP
What CP does the pontocerebellar tract use
MCP
what CP does the olivocerebellar tract use
ICP
aka climbing fibers
what CP does the trigeminal nerve use
all 3
how does the olivocerebellar tract work
- sensorimotor cortex sends info to IPSI olivary nuclei
- olivocerebellar tract sends info to CONTRA cerebellar cortex thru ICP (these are climbing fibers)
- climbing fibers branch, only one climbing fiber synapse per PKC
what is the main function of the olivocerebellar tract
involved in learning new motor skills
at rest: PKC complex spikes
with training: PKC simple spikes
what is the red nucleus up to
inputs: info from cerebral cortex descending to olive and info from cerebellum ascending to thalamus
output: inhibitory to IPSI olivary nucleus
basically can sense a mismatch between info leaving/going into cerebellum and can correct for it
How does the majority of info leave the cerebellum
SCP
What are the longitudinal zones of the cerebellum? What nucleus is associated with each?
(most medial)
vestibulocerebellum
-fastigial nucleus
spinocerebellum
-interposed nucleus
pontocerebellum
-dendate nucleus
Vestibulocerebellum: location, input, output, function
location: flocculonodular lobe, vermis
input: vestibular system
output: fastigial and vestibular nucleus
function: control eye mvmts in response to head, maintain balance
how does info leave the vestibulocerebellum
- from fastigial nucleus: bilateral projection to vestibular nuclei via ICP
- from vestibular nucleus control eyes thru MLF
- lateral vestibular nucleus mediates balance
Spinocerebellum: location, input, output, function
location: mostly paravermal area
input: spinal cord, brainstem (CN V)
output: interposed nucleus to:
- red nucleus
- VA/VL of thalamus to motor areas of cortex
function: posture, gait, coordination of trunk nd limb
how does info leave the spinocerebellum
- from interposed nucleus, leave thru SCP
- terminate in:
CONTRA reticular formation (regulate posture and locomotion)
CONTRA red nucleus (motor learning)
VA/VL thalamus
pontocerebellum: location, input, output, function
location: lateral cerebellum
input: motor cortex, basilar pons (MCP)
output: dentate nucleus to:
- red nucleus to ION
- VA/VL of thalamus to all motor areas
function: planning timing of mvmts (esp hand), coordination of speech
how does info get out the pontocerebellum (neo)?
- info from dentate nucleus, forms dentatorubrothalamic tract (this is the majority of the SCP)
- SCP decussates
- sends collaterals to red nucleus (to ION)
- synapses in VL of thalamus, then onto motor areas of the cortex
Describe the cerebella-thalamo-cerebro-cortical (CTCC) loop
Starting at cerebellar cortex:
- info from cerebellar cortex to deep cerebellar nuclei
- info from deep cerebellar nuc crosses midline, synapse in thalamus
- from thalamus, synapse in cerebral cortex
- from cerebral cortex, synapse in basilar pons
- from basilar pons, synapse back at cerebellar cortex
**if spinal cord included: info goes from cortex to spinal cord, then back into cerebellar cortex
What side of the body does one half of the cerebellum control?
IPSILATERAL
What symptoms would accompany a lateral hemisphere injury?
arms and speech fucked up
intention tremor
dysdiadochokinesia (rapid alt mvmts)
dysmetria (finger to nose test)
dysarthria (uneven, explosive phonation)
What symptoms would accompany a vermal injury?
trouble with posture
truncal ataxia
gait ataxia
What symptoms would accompany a vestibulocerebellar injury?
nystagmus (back and forth eye mvtms)
What happens if you have a stroke in your cerebellum?
cognitive defects, decrease reasoning power, inattention, patchy memory
dulling of emotional responses, aberrant emotional behaviors
