Cerebellum Flashcards
the cerebellum is located in ________ below the ________ (located in the ________)
the cerebellum is located in POSTERIOR CRANIAL FOSSA below the TENTORIUM CEREBELLI (located in the TRANSVERSE FISSURE)
what does the tentorium cerebelli support and protect?
tentorium cerebelli supports the occipital lobe and protects cerebellum from the weight of occipital lobe
what are the two hemispheres of the cerebellum seperated by?
the vermis
what side is the vermis most visible on?
posterior side
two _____ on the anterior surface and two _____ on the inferior surface are present on the cerebellum
two FLOCCULI on the anterior surface and two CEREBELLAR TONSILS on the inferior surface are present on the cerebellum
what are the three lobes of the cerebellum?
anterior, posterior and flocculonodular lobes
what are the anterior and posterior lobes seperated by?
the primary fissue
what are the posterior and flocculonodular lobes seperated by?
posterolateral fissure
what does the horizontal fissure divide?
divides the cerebellum into equal upper and lower halves
the _____ is the most inferior part of the vermis
the NODULES is the most inferior part of the vermis
the ______ are part of the posterior lobe, but posses no distinct function
the CEREBELLAR TONSILS are part of the posterior lobe, but posses no distinct function
where do the superior and inferior medullary vela merge?
at the fastigium
the superior cerebellar peduncles contains axons to/from the ________
the superior cerebellar peduncles contains axons to/from the MIDBRAIN
the middle cerebellar peduncles contains axons to/from the _______
the middle cerebellar peduncles contains axons to/from the PONS
the inferior cerebellar peduncles contains axons to/from the _______
the inferior cerebellar peduncles contains axons to/from the MEDULLA
all axons that enter/exit the cerebellum have to pass through the ________
all axons that enter/exit the cerebellum have to pass through the CEREBELLAR PEDUNCLES
the superior half of the cerebellum is supplied by one ________
the superior half of the cerebellum is supplied by one SUPERIOR CEREBELLAR ARTERY
the inferior half of the cerebellum is supplied by two ______ (_____ & _____)
the inferior half of the cerebellum is supplied by two INFERIOR CEREBELLAR ARTERIES (AICA & PICA)
the superior and anterior inferior (AICA) cerebellar arteries are branches of ________
the superior and anterior inferior (AICA) cerebellar arteries are branches of BASILAR ARTERY
posterior inferior (PICA) cerebellar arteries are branches of the ________
posterior inferior (PICA) cerebellar arteries are branches of the VERTEBRAL ARTERY
what are the four pairs of deep cerebellar nuclei?
1) ??
2) ?? = ?? + ??
3) ??
1) dentate nuclei
2) interposed nuclei = emboliform nuclei + globose nuclei
3) fastigial nuclei
what are the three neuronal layers of the cerebellar cortex?
- molecular cell layer
- purkinje cell layer
- granular cell layer
what 2 fibres does the cerebellum lack?
commissural and association fibres
mossy fibres include all afferent fibres (from ______) and target the _____ layer
mossy fibres include all afferent fibres (from EVERYWHERE) and target the GRANULAR layer
climbing fibres include only afferent fibres from _______ and targets the _____ layer
climbing fibres include only afferent fibres from INFERIOR OLIVARY NUCLEUS and targets the PURKINJE layer
what are the four main functions of the cerebellar?
1) regulates and coordinates _______
2) maintains ________ & ________
3) involved in _______
4) controls _______ side of body
1) regulates and coordinates VOLUNTARY MOVEMENTS
2) maintains BALANCE & POSTURE
3) involved in MOTOR LEARNING
4) controls IPSILATERAL side of body
describe the feedback mechanism.
motor actions get sent by the CNS and go to the muscle, tendon and joint action and from the action we get some sensory feedback to the CNS
what is sensory feedback?
sensory feedback is required by motor centres to monitor whether motor actions are progressing in accordance to the motor plan, and if adjustments are required
describe (and draw) the feedback system pathway.
- motor action gets sent down via pyramidal and extrapyramidal pathways
- goes to skeletal muscles to activate (another copy ‘motor plan copy’ is sent to the cerebellum via the mossy fibres)
- depending on how the movement went, we get sensory feedback about the movement (via muscle spindles & GTOs) and that gets sent back via the posterior spinocerebellar pathway (lower limbs) and cuneocerebellar pathway (upper limb)- this gives us feedback on how the movement actually went
- the feedback is sent to the cerebellum via mossy fibres or/and an error signal is sent to the cerebellum via climbing fibres
- the cerebellum compares motor actions w/ sensory feedback and can detect errors between the action and the feedback
- if needed, error correction is sent from the cerebellum to the motor action via output of climbing fibres
(see notes for drawing)
is the feedback system suitable for slow or fast movements?
slow movements
describe (and draw) the feed forward system pathway.
- motor action is sent via pyramidal and extrapyramidal pathways to the skeletal muscle and a motor plan copy is sent to the cerebellum via the mossy fibres
- also get sensory information sent into the cerebellum in advance via mossy fibres telling us where we are in space, the position of our body and info about previous learned experience
- cerebellum integrates those and makes a predicted output about how the plan should go
- cerebellum predicts outcome of motor actions based on sensory information and prior experience (is a predictor) or it recommends a plan
- cerebellum modulates/adjusts motor actions before an error occurs (is a modulator) and it anticipates a suitable motor action to produce smooth and precise movements
(see notes for drawing)
is the feed forward system suitable for slow or fast movements?
fast movements
what is the vestibulocerebellum composed of?
flocculonodular lobe and fastigial nuclei
where does the vestibulocerebellum receive its projection from?
from vestibular nuclei and vestibular nerve
what is the vestibulocerebellum function?
influences the activity of vestibular nuclei, for purposes of error correction
describe (and draw) the vestibulocerebellar loop.
- get info sent from the vestibular nuclei about where our head is in space and how tilted it is (and so forth)
- it gets sent to the flocculonodular lobe via the vestibulocerebellar tract (there is an afferent copy that gets sent to the fastigial nuclei- for integration purposes as it compares sensory information to see of there are any errors)
- from the flocculonodular lobe, it comes up with an appropriate plan and sends it to the fastigial nuclei (via the efferent pathway from the cortex)
- from there it goes back to the vestibular nuclei via the cerebello-vestibular tract (what gets sent back is the adjusted motor plan)
- from the vestibular nuclei it goes through the vestibulospinal tract to the spinal cord where it modulates skeletal muscles
(see notes for drawing)
what is the spinocerebellum composed of?
composed of the anterior lobe (without the nodule), intermediate hemisphere, fastigial and interposed (emboliform and globose) nuclei
where does the spinocerebellum receive its input from?
from ipsilateral spinal cord mainly concerning unconscious proprioception through the posterior spinocerebellar and cuneocerebellar tracts
what is the spinocerebellum function?
regulates muscle tone, posture and balance
describe (and draw) the spinocerebellar loop.
- initially gets sensory emission from the spinal cord via the spinocerebellar tracts giving us information about where our body is in space (afferent copy sent to the fastigial and interposed nuclei)
- it goes to the regions in the cerebellum -> it adjusts the motor plan and sends to the fastigial and interposed nuclei via the efferent pathway from the cortex
- it then compares the sensory to the motor and sends out an adjusted plan to the brainstem (specifically to the red nucleus, reticular formation, vestibular nuclei)
- then goes through the extrapyramidal pathways (rubro-, recticulo-, vestibulospinal tracts) to the spinal cord -> skeletal muscles
(see notes for drawing)
what is the cerebrocerebellum composed of?
composed of lateral hemispheres and dentate nuclei
where does the cerebrocerebellum receive its input from?
receives projections primarily from contralateral motor cortex
what is the cerebrocerebellum function?
coordinates fast and alternating movements (e.g. writing and speech production) by planning the movements w/ regard to their direction, timing and force (muscle strength)
describe (and draw) the cerebrocerebellar loop.
- starts at the motor cortices (with input all over but specifically the premotor cortex) -> to the pontine nuclei via the corticospinal tract (afferent copy is sent to the dentate nuclei)
- crosses over to the other side and goes to the lateral cerebellar hemipsheres via the ponto-cerebellar nuclei
- dentate nuclei via the efferent pathway from cortex when it integrates information then sends to back to the thalamus via the dentatothalamic tract
(also have another output from dentatothalamic tract to the red nucleus which is called the dentatorubral tract) - from the thalamus it goes back to the cortex via the thalamocortical tract -> pyramidal tract to the spine
(contralateral side)
(see notes for drawing)
what loop lesions cause truncal ataxia?
spinocerbellar and vestibulocerebellar
what loop lesions cause limb ataxia?
cerebrocerebellar
why do you get ataxic gait during alcohol consumption and what loop does it relate to?
you have a lack of coordinate gait due to your loss of balance because there is a lack of error correction in recticulospinal and vestibulospinal tracts == spinocerebellum
why do you get involuntary & uncoordinated eye movements during alcohol consumption and what loop does it relate to?
you get ataxia of the eye due to lack of error correction is vestibulo-ocular reflex == vestibulocerebellum
why does slurry speech occur during alcohol consumption and what loop does it relate to?
due to lack of error correction in corticonuclear tract == cerebrocerebellum
why do you have a loss of skilled movement (dyspraxia) during alcohol consumption and what loop does it relate to ?
due to lack of error correction in corticospinal tract == cerebrocerebellum
