Lecture 15 Cerebellum Flashcards
What is the cerebellum often called?
The great comparator
cerebellum compares the intended vs. actual
movements to make needed adjustments
what is cerebellar white matter called?
Arbor Vitae
The cerebellum is __% of total brain volume, but has almost __x more neurons than cerebral cortex
10%
x4
True or false: The cerebellum directly connects to LMNs
False, there is no direct connection to the motor neurons
Note: Basal ganglia also has no direct connection to motor neurons
True or false: Damage to the cerebellum causes severe muscle weakness
False.
Severe damage does not cause direct muscle weakness or
sensory perception issues
* Causes coordination and postural control deficits
* Somewhat decreased cognitive and emotional function
What are the 4 Deep Cerebellar Nuclei called?
- Dentate
- Emboliform
- Globuse
- Fastigial
Note: Emboliform and Globuse are both “interposed”
What are the 3 functional divisions of the cerebellum?
- Vestibulo-cerebellum
- Spino-cerebellum
- Cerebro-cerebellum
The superior peduncle is for _______ (efferents/afferents)
Middle is for: ________
Inferior is for ____________
Superior: Mostly efferents
Middle: ONLY afferents
Inferior: Both afferents and efferents
What does the superior cerebellar peduncle relay to?
Projecting to motor nuclei of thalamus +
Red Nuclei
Afferents from the anterior spinocerebellar tract travels through which cerebellar peduncle?
Superior
Efferents from the vestibulospinal and
reticulospinal tracts travel through what peduncle?
Inferior
Purkinje cells ________(Inhibit/excite) cerebellar and
vestibular nuclei
Inhibit
Think of these as the internal Globus Pallidus of the cerebellum they just inhibit
Mossy and climbing fibers transmit
afferent __________(Excitatory or inhibitory) neurotransmitters
excitatory
Where do mossy fibers start?
Brainstem and spinal cord
Where do climbing fibers start?
Inferior olive
All 3 cortical layers of the cerebellum are what kind of matter? (Gray or white)
Gray
What is the largest and most lateral cerebellar nuclei?
Dentate
Note: most medial is “Fastigial”
A functional unit of the cerebellar cortex consists of:
Purkinje cell (inhibitory) + _____________
Deep nuclear cell (excitatory)
What are the 2 interposed deep cerebellum nuclei called?
Emboliform
Globose
Dentate nucleus
What does the flocculonodular lobe do?
Also what is another name for it?
Balance and vision
Vestibulocerebellum
The vermis and intermediate zones are also called?
What do they do?
Spinocerebellum
Proximal and distal movements
What is the only part of the cerebellum that receives info directly from the spinal cord
spinocerebellum
(Vermis and intermediate zones)
What deep cerebellum nuclei is a part of the vermis?
What deep cerebellum nuclei is a part of the intermediate zone?
Fastigial Nucleus (most medial)
Both interposed nuclei
The vermis is responsible for….
Proximal gross movements of body and limbs
The intermediate zone is responsible for…
Distal voluntary movement
The lateral hemispheres of the cerebellum are also called
What nuclei is present here?
What is the function?
Cerebrocerebellum
Dentate
Regulates highly skilled movements/motor planning
True or false: cerebellum blood supply does not match the division of the lobes
True
The superior cerebellar artery supplies what?
Supplies superior and middle
cerebellar peduncles
The AICA supplies what parts of the cerebellum
Supplies middle cerebellar peduncle,
anterior inferior cerebellum including
flocculus
The PICA supplies what area of the cerebellum
Supplies the tonsils, inferior vermis,
inferior cerebellar peduncle, and
inferior aspects of cerebellar
hemispheres
What are the inputs of the vestibulocerebellum?
Where do they synapse?
Inputs- Ipsilateral vestibular nuclei/apparatus
and visual cortex
Where do they synapse: flocculonodular lobe
What are the outputs of the vestibulocerebellum?
- Project to vestibular nuclei
- Postural control by lateral and medial
vestibulospinal tracts - Eye movements
Note: Vestibulospinal tracts synapse in the vestibular nuclei
Which part of the cerebellum deals with high fidelity information?
Spinocerebellum
What tracts are involved with the spinocerebellum?
Do these give info from contralateral side of body or ipsilateral side?
Posterior Spinocerebellar
Cuneocerebellar
Ipsilateral (uncrossed)
Rostrospinocerebellar (ipsilateral)
Anterior spinocerebellar (cross twice)
What is the function of the posterior spinocerebellar tract?
LE proprioception
Note:
1st order synapses in clarkes nucleus -> 2nd order is the posterior spinocerebellar pathway -> ipsilateral cortex
What is the purpose of the cuneocerebellar pathway?
Proprioception of neck and UE
note: first order neurons synapse in lateral cuneate nucleus -> ipsilateral cuneocerebellar pathway -> ipsilateral cortex
What are the two high fidelity pathways called?
Cuneocerebellar and posterior spinocerebellar
True or false: anterior spinocerebellar and rostrospinal are high fidelity pathways
False, they are internal feedback tracts
Where does the anterior spinocerebellar tract cross?
What is it for?
Crosses in thoracolumbar gray matter
Crosses again in midbrain
Coordinates Both LE (internal feedback)
Where does the rostrospinal tract start?
Where does it cross?
Cervical spine - T1
Uncrossed
Note: travels through both superior and inferior cerebellar peduncles
Which parts of the cerebellum directly transmit info to motor neurons?
None!
The pathway that describes the outputs of the vermis is:
Purkinje cells -> ___________ ->
brainstem -> thalamus -> Cortex
Fastigial Nucleus of vermis
In the spinocerebellum intermediate zone, purkinje cells project to the….
Interposed Nucleus
What is the “Closed cerebro-cerebello-cerebral loop”
- Involved with motor planning and timing
of movements - Changes in neural activity in dentate
starts before that of cerebral cortex
prior to execution of movement
What is the pathway of the Closed cerebro-cerebello-cerebral loop
Motor and premotor cortices (cerebral) -> pontine
nuclei -> lateral cerebellar cortex -> dentate
nucleus -> thalamus -> cerebral
cortex
Note: the pontine nucleus is on the way to the cerebellum, the dentate nucleus is on the way back to the cortex.
True or false: Inputs AND outputs of the “Closed cerebro-cerebello-cerebral loop” cross
True
The inferior olivary nuclei project through where?
Inferior cerebellar peduncle
Cerebral Cortex is by far the most important input to the cerebellum, though it doesn’t directly communicate.
The pathway goes:
Cortex -> Synapse on ipsilateral ________ -> pontocerebellar fibers project -> _______________ -> contralateral cerebrocerebellum
pontine nuclei
Middle peduncle
The vestibular nuclei projects to the vestibulocerebellum through what peduncle?
inferior
The Dorsal spinocerebellar and cuneocerebellar tracts project to the spinocerebellum via what peduncle?
Inferior
Spinocerebellar afferents arise
from ___________(Ipsilateral/Contralateral) sources
Most cerebellar efferents to motor
tracts remain ___________(Ipsilateral/Contralateral)
Ipsilateral
Ipsilateral
Even the ones that cross end up crossing twice so it’s still ipsilateral. This is why most cerebellar dysfunctions will be ipsilateral!
Nystagmus, Unsteadiness, truncal ataxia, disequilibrium are all signs of a cerebellum dysfunction where?
Vestibulocerebellum
What is the cardinal sign of cerebellum dysfunction?
Ataxia
What kind of tone is most commonly seen with cerebellum dysfunction, hypo or hyper?
Hypotonia
Ataxic finger movements and Dysarthria are commonly seen with what cerebellum dysfunction?
Cerebrocerebellum
Dysarthria
Scanning/explosive speech: ataxia of speech
Limb ataxia
Dysdiadokinesia
Dysmetria
Action tremor: shaking of limb during movement
Intention tremor
These are all commonly seen with what cerebellum dysfunction?
Spinocerebellum
- Loss of check/rebound: quick removal of resistance causes exaggerated response
- Movement decomposition: attempting to move 1 joint at a time
- Tends to be compensation for movement difficulties
These are all commonly seen with what cerebellum dysfunction?
Spinocerebellum
Why do intention tremors occur?
Tends to occur due to delays in agonist burst of activity + in antagonist’s ability to brake
How can you differentiate between sensory ataxia and cerebellar ataxia?
People with cerebellar ataxia with preform simularly with eyes open and eyes closed
People with sensory ataxia will improve with visual aid
What pathway is interupted in people with sensory ataxia?
DCML
The finger to nose task is good for revealing what kind of symptom?
Dysmetria and intention tremors
-intention tremors get worse the closer they get to their nose
Cerebellum feedfoward vs feedback
Cerebellum anticipates the motor output needed to perform movement (feedforward)
and then monitors what is happening to make adjustments as necessary (feedback)
Motor learning allows better ___________ (feedforward/feedback) of movement by reduction of errors that require slower ________ (feedforward/feedback) mechanisms to improve movement
feedfoward; feedback
At cellular level, _________ can selectively cause long term depression in synapses between parallel fibers and Purkinje cells that are simultaneously being activated by climbing fibers
* This depression can last minutes to hours
Climbing fibers
1
Midbrain
2
Primary Fissure
3
Folia & Posterior Lobe
4
Pons
5
Middle Cerebellar Peduncle
6
Tonsils
7
Medulla
8(space)
4th ventricle
9
Posterior Lobe
10
Cerebral Aqueducts
