Sievert: Cerebellum Flashcards
What is the primary function of the cerebellum?
to detect differences in “motor error” - the error between the intended movement and the actual movement
What happens to neuronal activity in the cerebellum during the course of movement?
it is constantly changing - the neural processing is dynamic
In general, what do patients with cerebellar damage have problems with?
range, rate, and direction of movement
What are four problems that can arise as a result of damage to the cerebellum?
cerebellar ataxia
dysmetria (can’t follow finger w eyes)
dysdiadochokinesia (hand flap)
**tremor when asked to perform a particular motion
What is unique about the tremor associated with cerebellar damage?
when you ask a patient to perform a particular movement (i.e. touch their nose), the tremor gets worse as they approach the end point
What are the three cerebellar peduncles?
superior
middle
inferior
What are the three deep cerebellar nuclei?
fastigial nucleus
interposed nucleus
dentate nucleus
In a ventral view of the cerebellum, 3 cerebellar peduncles can be seen, as well as which lobe of the cerebellum?
vestibulocerebellum *floculo-nodular lobe
The midline of the cerebellum and the paramedian areas comprise which lobe?
spinocerebellum
The lateral lobes of the cerebellum comprise which lobe?
cerebrocerebellum
receives input from the spinal cord related to spindle information and the cortex related to execution of movements for fine control of proximal and distal muscles
spinocerebellum
receives input from the premotor cortex and sensory association areas related to the planning of movements
cerebrocerebellum
receives input from the vestibular system and the visual system to control eye movements and balance
vestibulocerebellum
What nuclei does the spinocerebellum project to?
fastigial and interposed nuclei
What nuclei does the cerebrocerebellum project to?
dentate nucleus
What nucleus does the vestibulocerebellum project to?
vestibular nuclei
*vestibulocerebellum has no nuclei to project to within the cerebellum, so it leaves and travels to the vestibular nuclei
Each cerebellar hemisphere has control over the (blank) side of the body. So, any inputs to the cerebellum from the cortex must (blank) and inputs from the spinal cord or vestibular nuclei must remain (blank). Similarly, outputs from the cerebellum to the cortex must also (blank) back on their way up to cortex
same; cross; ipsilateral; cross
mostly efferent pathway arises from cell bodies in deep cerebellar nuclei and crosses in the midbrain on the way to the thalamus. The correction.
superior cerebellar peduncle
The superior cerebellar peduncle is mostly what? Where does it arise from? Where does it cross on its way to the thalamus? What is its role?
mostly efferent;
arises from cell bodies in the deep cerebellar nuclei;
crosses in the midbrain;
the correction
afferent pathway arises from cell bodies in the contralateral pontine gray which got their input primarily from the ipsilateral cerebral cortex. What the muscle are supposed to do.
middle cerebellar peduncle
The middle cerebellar peduncle is a (blank) pathway. What does it arise from? What is its role?
afferent; arises from cell bodies in the contralateral pontine gray which got their input primarily from the ipsilateral cerebral cortex; what the muscles are supposed to do
Mostly afferent pathway whose fibers come from cells in the spinal cord, inferior olive, vestibular nuclei and ganglion. Efferents of this peduncle project to the vestibular nuclei. What the muscles are doing.
inferior cerebellar peduncle
The inferior cerebellar peduncle is mostly an (blank) pathway. Where do its fibers come from? Where do efferents of this peduncle project to? What is its role?
afferent; fibers come from cells in the spinal cord, inferior olive, vestibular nuclei and ganglion; efferents project to the vestibular nuclei; what the muscles are doing
What is projecting into the cerebellum?
What is projecting out?
What is receiving from the deep nuclei?
What is the dominant source of inputs to the pontine nuclei?
brainstem and spinal cord structures; deep nuclei; VA/VL complex of thalamus; cortex
What is projecting into the cerebellum?
brainstem and spinal cord structures
What is projecting out of the cerebellum?
deep nuclei
What is receiving input from deep nuclei?
VA/VL complex of thalamus
What is the dominant source of inputs to the pontine nuclei?
cortex
Where do the major inputs to the cerebrocerebellum come from?
cerebral cortex: frontal and parietal lobes motor and premotor cortex sensory cortex cingulate cortex
What are the inputs to the cerebrocerebellum responsible for?
planning of movements
What is the pathway from the cerebellar cortex to the primary motor cortex?
cerebellar cortex –> deep cerebellar nuclei –> (projections to red nucleus and superior colliculus) –> ventral lateral complex of thalamus on opposite side –> primary motor and premotor cortex
Again, what is the pathway from cerebellar cortex to primary motor and premotor cortex?
cerebellar cortex –> deep cerebellar nuclei –> (superior cerebellar peduncle) –> VL complex of the thalamus on the opposite side –> primary motor and premotor cortex
The cerebrocerebellum projects to which deep cerebellar nuclei? Where does it project to from there? Why?
dentate nucleus; premotor cortex; motor planning
The spinocerebellum projects to which deep cerebellar nuclei? Where does it project from there? Why?
interposed and fastigial nuclei; motor cortex and brainstem; motor execution
The vestibulocerebrum projects to which nuclei? Then where does it go? Why?
vestibular nuclei; lower motor neurons in spinal cord and brainstem; for balance and vestibulo-ocular regulation
Which lobe of the brainstem is involved in motor planning?
cerebrocerebellum
Which lobe of the brainstem is involved in motor execution?
spinocerebellum
Which lobe of the brainstem is involved in balance and vestibulo-ocular regulation (VOR)?
vestibulocerebellum
How do cerebellar afferents get from the cortex to the cerebrocerebellum? Is this pathway crossed?
via pontine nuclei and MCP; crossed
How do cerebellar afferents get from the olive to all parts of the cerebellum? Is this pathway crossed?
via the ICP (climbing fibers); crossed
How do cerebellar afferents get to the vestibular nuclei, accessory cuneate nucleus, and Clarke’s nucleus? Is this pathway crossed?
via the ICP; no!
Describe the afferent pathway from the frontal/parietal cortex to the cerebellar cortex.
frontal/parietal cortex –> red nucleus –> inferior olive (cross to other side) –> inferior cerebellar peduncle –> cerebellar cortex/deep nuclei
Or
frontal/parietal cortex –> pontine nuclei –> middle cerebellar peduncle (cross to other side)–> cerebellar cortex/deep nuclei
How do afferents get from the pontine nuclei to the cerebellar cortex/deep nuclei?
middle cerebellar peduncle
How do afferents get from the inferior olive to the cerebellar cortex/deep nuclei?
inferior cerebellar peduncle
Cerebellar cortex can also receive direct input from the (blank) and the (blank)
spinal cord; vestibular nuclei
Where does spinal cord input to the cerebellar cortex come from?
Clarke’s column (C8 and below)
The origin of the dorsal spinocerebellar tract which carries information about muscle length, tension and velocity to the cerebellum from muscles below C7.
Clarke’s column
What does Clarke’s column carry information about?
muscle length, tension, and velocity
What levels does Clarke’s column carry information from?
muscles below C7 (C8 and below)
The upper limb equivalent for Clarke’s column carrying muscle information from C7 and above to the cerebellum over the ICP.
accessory cuneate nucleus
What does the accessory cuneate nucleus carry muscle information from?
C7 and above
What do Ia fibers from the muscle spindle carry info about?
length and rate of change
What do Ib fibers from the GTO carry info about?
tension
What do II fibers from the muscle spindle carry info about?
length
Clarke’s column is found in the dorsal horn between what spinal levels? What is it the beginning of?
C8 and L3; the beginning of the dorsal spinocerebellar tract
Axons in Clarke’s column receive muscle information which then ascends to the cerebellum in the ICP on the (blank)
dorsal spinocerebellar tract
Above C8, muscle information travels to the (blank) nucleus instead of Clarke’s
accessory cuneate nucleus
What are the three major layers in the cerebellar cortex?
molecular layer
purkinje cell layer
granule cell layer
What layer of the cerebellar circuitry is this?
purkinje cell dendritic tree with numerous parallel fiber endings
molecular layer
What layer of the cerebellar circuitry is this?
Large cell bodies of Purkinje cells
Purkinje cell layer
What layer of the cerebellar circuitry is this?
Granule cells, mossy fibers and climbing fibers entering cortex
granule cell layer
Where are the deep cerebellar nuclei located?
in the white matter layer
What are the two major excitatory inputs?
mossy fibers
climbing fibers
Fibers that originate in: the contralateral pontine nuclei, the ipsilateral Clarke’s column and Accessory Cuneate nucleus, the vestibular nuclei and ganglion, and reach the cerebellar cortex where they excite granule cells. Any fiber that is not from the Olive
Mossy fibers
All mossy fibers send an excitatory collateral to the (blank)
deep nuclei
Fibers that originate in the contralateral inferior olive and reach all areas of the cerebellar cortex where they send an excitatory input to the purkinje cell dendrites after sending excitatory collateral to the depp nuclei
climbing fibers
Incoming mossy and climbers fibers have an excitatory collateral to the (blank)
deep nuclei
These are inhibitory to the deep nuclei and are the only way out of the cortex
purkinje cells
What is the only way to get info out of the cerebellum?
turn the purkinje cells off momentarily and allow the deep nuclei to be driven by the mossy and climbing fibers
All fibers projecting into the cerebellar cortex are (blank) (mossy fibers, climbing fibers & granule cell parallel fibers) that means the granule cells are (blank).
excitatory; excitatory
All cells of the cerebellar cortex except the (blank) are inhibitory (Purkinje cells, stellate cells, basket cells and Golgi cells).
granule cells
The deep cerebellar nuclei (not part of the cerebellar cortex) are (blank)
excitatory
The only way out of the cortex is an inhibitory (blank) which must be turned off to allow the deep nuclei to fire.
purkinje cell axon
What do lesions of the cerebellar hemisphere result in?
ipsilateral incoordination/ataxia
What will a lesion in the RIGHT cerebellar hemisphere result in?
motor incoordination on the RIGHT side
Will a lesion in the inferior or middle peduncle cause an ipsilateral or contralateral deficit?
an ipsilateral deficit
Will a lesion in the superior cerebellar peduncle cause an ipsilateral or contralateral deficit?
it depends on if it is before or after the decussation
A lesion of the RIGHT superior cerebellar peduncle before the decussation will
also result in motor incoordination/ataxia on the RIGHT side. However, a lesion after the decussation of the superior
cerebellar peduncle will result in CONTRALATERAL motor deficits
If there was a lesion where the superior peduncles are crossing, what kind of deficit would this produce?
bilateral deficit
A lesion in the superior peduncles after they have crossed sides would result in what kind of lesion?
ipsilateral
Cerebellar lesions typically result in irregular uncoordinated movement called (blank)
ataxia
What do spinocerebellar lesions usually result in?
unsteady gait (balance) and eye movement abnormalities
What do vestibulocerebellar lesions usually result in?
problems with balance and eye movements
When the cerebellum is damaged, what reflex fails to operate correctly?
VOR
*this was shown in monkeys who were given glasses to magnify or minify their vision
What are the 3 distinct layers of the cerebellar cortex?
molecular layer
purkinje layer
granule layer
Where is all output from the cerebellar cortex carried? What carries it?
into cerebellar white matter;
purkinje cells
What is the ONLY output cell of the cerebellar cortex?
purkinje cells
Are purkinje cells excitatory or inhibitory?
inhibitory
What are the deep cerebellar nuclei?
fastigial
globose
emboliform
dentate
The outputs of cerebellar nuclei are all (blank)
excitatory
Climbing fibers originate exclusively from the (blank). They ascend and provide a direct excitatory input to Purkinje cells.
inferior olivary complex
(blank) originate from all other sources and ascend to form excitatory synaptic inputs to granule cells, which in turn excite the Purkinje cells via parallel fibers
mossy fibers
Both climbing and mossy fibers are (blank)
excitatory
IMPORTANT principle with cerebellar lesions is that deficits in coordination occur (blank) to the lesion
ipsilateral
Each cerebellar hemisphere is concerned with the (blank) side of the body. Therefore, the right cerebellum controls the right side of the body, while the left cerebellum controls the left side of the body
ipsilateral
Where do output axons from the dentate, globose and emboliform nuclei all cross?
at the decussation of the superior cerebellar peduncle
