Cerebellum Flashcards
What are the functions of the cerebellum?
Coordinates movements
Maintains posture
Motor learning and procedural memory
What kind of input does the cerebellum receive?
Sensory input but does not discriminate nor interpret what the sensory input it
Will a lesion to the cerebellum lead to muscle paralysis ?
Not usually
What are the 4 layers of the cerebellum?
Molecular layer
Purkinje layer
Granular layer
White matter layers
Where is the molecular layer of the cerebellum?
What cells are w/in it?
Gray matter next to pial surface
Very few neurons, cell bodies of basket cells and stellate cells
What is contained in the purkinje layer?
Gray matter of the cerebellum w/ purkinje cell bodies
What layer is the granular layer of the cerebellum?
What odes it contian?
Deepest layer
Granule and golgi cells
All the neurons in the gray matter of the cerebellum are inhibitory, except for which?
Granule cells
What do purkinje cells do?
Efferents or afferents?
NTR released?
Efferents
Inhibit cerebellar nuclei and vestibular nuclei
GABA
What do Granule cells do?
Efferents or afferents?
NTR released?
Efferents
Smallest but only excitatory neuron
Glutamate
What do Stellate cells do?
Efferents or afferents?
Characterization?
Efferent;
Synapse w/ purkinje and inhibit them
Star shaped dendrites
What are golgi cells?
NTR?
Characteristics?
Inhibitory neurons that release GABA
Large cell body w/ short axons
What do axons of basket cells synapse with?
With purkinje cells
Inhibit them
What two cells synapse with purkinje cells to inhibit them?
Stellate cells
Basket cells
What are the afferent fibers of the cerebellum?
Mossy and climbing fibers
What do climbing fibers synapse w/ ?
Purkinje cell
Deep cerebellar nuclei
Where do climbing fibers originate from?
Inferior olive
What do climbing fibers convey info about?
Movement ERRORS to cerebellum
What do mossy fibers synapse w/?
Deep cerebellar nuclei
Granule Cells
Where are mossy fibers from?
(Everywhere but inferior olive)
Sc, RF, vestibular system, and pontine nuclei
What type of info do mossy fibers convey to cerebellum
Somatosensory
Arousal
Equilibrium
Cerebral cortex motor into
What are the 3 functional division of cerebellum?
Vestibulocerebellum (archicerebellum)
Spinocerebellum (paleocerebellum)
Cerebrocerebellum (pontocerebellum)
What makes up the vestibulo-cerebellum?
Flocculonodular lobe (flocculus and Nodulus)
What is the input to the vestibulocerebellum?
Output to?
Info from vestibular receptors, from visual areas
Output to vestibular nuclei
What are the functions of the vestibulocerebellum?
Balance
equilibrium
eye movements
neck and trunk movements (postural ms. Of head and body)
What makes up the spinocerebellum?
Vermis and paravermal regions
What info comes into the spinocerebellum?
Somatosensory info
Visual auditory, vestibular info
In spinocerebellum,
Where does somatosensory info go?
Where does visual, auditory and vestibular info go?
Somatosensory —> Medial UMNs —> medial tracts
Vis., Aud., Vestibulo., —> lateral UMNs —> lateral tracts
Where are all medial tracts?
What are they?
All in anterior funiculus
Medial reticulospinal, vestibulospinal, corticospinal, and lateral vestibulospinal
What are the lateral tracts?
Rubrospinal
Lateral reticulospinal, corticospinal
What are the functions of the spinocerebellum?
Important for gait and station
Axial and lower extr. Movement
What comprises the cerebrocerebellum?
Lateral hemispheres of cerebellum
What in the input to the cerebrocerebellum ? Via what?
Input from cerebral cortex
Via pontine nuclei
What are the functions of the cerebrocerebellum?
Coordination
Planning
Timing
(Mainly for UE)
How do afferents enter the cerebrocerebellum?
Via MCP
How do afferents enter the spinocerebellum?
Inferior cerebellar peduncle
How do afferents enter the vestibulocerebellum?
Inferior cerebellar peduncle
What type of afferent fibers are those going into the spinocerebellum?
From what tract?
All mossy fibers
ASCT
PSCT
Cuneocerebellar
What type of afferent fibers are those going into the vestibulocerebellum?
From what tracts?
Mossy fibers
Vestibular nucleus and CN 8
What type of afferent fibers are those going into the cerebrocerebellum?
Form what tracts?
Mossy fibers from..
- cortico-pontocerebellar
- Cortico-reticulocerebellar
Climbing fibers from …
cortico-olivocerebellar fibers
What region of the body does the ASCT and PSCT carry info from?
Leg
What region of the body does the Cuneocerebellar tract carry info from?
Arm
What is the pathway of the PSCT?
1st order axons via DRG and ascends in Gracile Fasciculus
Synapses in Nucleus Dorsalis of Clarke
2nd order axons ascend in PSCT
Enter inferior cerebellar peduncle to go to Spinocerebellum (spinocerebellum will send out via medial or lateral tracts)
What is the pathway of the cuneocerebellar tract?
1st order axons via DRG enters SC and ascends in Cuneate Fasciculus
Synapses in Accessory Cuneate Nucleus in lower medulla
2nd order axons ascends in CunC T.
Enter via ICP to spinocerebellum
What is the pathway of the ASCT?
1st order from intermediate gray matter crosses via AWC to ASCT
Ascends to SCP
Crosses again to Cerebellum
How do most efferent fibers leave the cerebellum?
Via the SCP from globose, emobliform and dentate nuclei
What goes thru MCP?
Afferents from pontine Nuclei relayed by cortex
What makes up the ICP?
Juxtarestiform body
Restiform body
What ar the deep nuclei of the cerebellum?
Dentate
Fastigial
Emboliform
Globose
What are the “interposed nuclei”
Globose and Emboliform nuclei
How is info transmitted from the functional divisions of the cerebellum to the deep nuclei?
Via purkinje fibers
What does the vestibulocerebellum bypasses? How? And to where?
Bypasses deep nuclei of cerebellum
Via purkinje fibers
To vestibular nucleus
What deep nuclei does the cerebrocerebellum send efferent purkinje cells to?
Dentate
Interposed
What deep nuclei does the spinocerebellum send efferent purkinje cells to?
All of them
What deep nuclei does the vestibulocerebellum send efferent purkinje cells to?
Where else?
Fastigial nucleus
Also to vestibular nucleus but without going thru deep nuclei
Where does the dentate nucleus send efferents to?
Red nucleus —> RuT.
VLN of thalamus —> OPPOSITE MOTOR CORTEX —> CST
Where does the interposed nuclei send efferent to?
Red nucleus —> RuT
Red nucleus —> inf. Olivary nucleus —> olivocerebellar fibers to correct motor errors
VLN of thalamus —> Motor cortices —> CST
Where does the fastigial nucleus send info to?
Reticular formation —> reticulospinal tract (for posture)
Vestibular nucleus —> Vestibulospinal tract (extensor)
What will a unilateral lesion to the cerebellum cause?
Why?
Cause ipsilateral ataxia
Bc crosses to opposite motor cortex —> CST which will CROSS AGAIN
(Now on same side again)
What will a lesion to the vestibulocerebellum cause?
Nystagmus
Truncal ataxia
Titubation (truncal instability)
Cannot tandem walk
What will a lesion of the spinocerebellum cause?
Problems with gait
Truncal ataxia - wide base, staggering base
What will a lesion to the cerebrocerebellum cause?
Dysarthria Scanning speech Ataxic gait W/ tendency to fall TOWARD lesion Decomposition of movements Appendicular ataxia
What are the manifestations of appendicular ataxia?
Dysdiadochokinesia
Dysarthria - scanning speech
Dysmetria
Action tremors
Hypotonia
Decomposition of movement
What is dysdiadochokinesia?
Inability to rapidly alternate movements
What is dysmetria?
Inability to accurately move an intended distance
What is an action tremor?
Shaking of the limb during voluntary movement
What is the vestibulocerebellum a connection between?
B/w vestibular system and flocculonodular lobe
What is the spinocerebellum a connection b/w?
B/w curators and proprioceptive info coming from SC to vermis and paravermis regions
What does the cerebrocerebellum connect?
Connection bw/ cerebral cortices and cerebellum
What is common to all lesions of the cerebellum
Ataxia
What is ataxia?
Voluntary, normal strength, jerky and inaccurate movements
Wide based, guarding, tend to fall to side of lesion
“Druken sailor gait”
What is midline ataxia?
What causes this?
Ataxia syndromes caused by vestibulocerebellar and spinocerebellar diseases
Truncal instability w/ Titubation and gait ataxia
Where is the Nucleus Dorsalis of Clarke?
Gray matter from C8-L2
What is cerebellar ataxia vs. sensory ataxia?
Both will have a positive Romberg test
But
Cerebellar will have normal vibratory sense, etc.
Sensory will have abnormal vibratory sense, proprioception and ankle reflexes due to damage at Posterior Columns
What should you do to test the function of the vestibulocerebellum and spinocerebellum?
Station
Walking
Tandem gait
How should you test the cerebrocerebellum functions?
Rapid alternating movements Finger to nose Toe to finger Heel to shin Rebound and check reflex Speech Ataxia
