Cerebellum Flashcards
lesion to cerebellum leads to?
- gait imbalance, poor postural control
- poor coordination of voluntary movements, slurred speech
(note: movement still allowed but not controlled well)
Via which tracts does the cerebellum compare willful command with muscle tension, joint position, and tone? Are the tracts ipsilateral or contralateral?
ipsilateral spinocerebellar tracts
which 2 afferent tracts does the cerebellum receive? which peduncles do the tracts pass through? What do the tracts innervate? Indicate which tract has motor afferents and which has sensory afferents?
- corticopontocerebellar tract: middle cerebellar peduncle (MCP), premotor and motor cortex (MOTOR AFFERENTS)
- spinocerebellar tracts: inferior cerebellar peduncle (ICP), upper and lower limbs (SENSORY AFFERENTS)
lesions to corticospinal tract have ______________ effects, whereas, lesions to the cerebellum have ________________ effects. (contralateral/ipsilateral)
- corticospinal tract lesion = contralateral
- cerebellum lesion = ipsilateral
TRUE or FALSE: Cerebellum only acts before the movement.
FALSE: acts before and during movement (to correct for errors)
What is ataxia? Lesion to which brain region/structure causes this? Is there a tendency to fall to the same or opposite side of the lesion - why?
- lack of coordination of muscle movements
- lesion to cerebellum
- fall to same side as lesion b/c cerebellum lesion = ipsilateral
What are 2 types of ataxia?
- dysmetria = overshooting goal in reaching for target
- dysdiadochokinesia = inability to perform rapid alternating movements
What is a forced ‘intentional’ tremor? Lesion to which brain region/structure causes this?
- tremor during purposeful movements (i.e. while moving)
- lesion to cerebellum
Gyri are to the cerebrum as _________ are to the cerebellum.
folia
Sulci are to the cerebrum as _________ are to the cerebellum.
fissures
Which 3 arteries supply the cerebellum?
- superior cerebellar artery
- PICA
- AICA
What are the 3 cerebellar peduncles? Which ones hold afferent tracts and which ones hold efferent tracts?
- superior cerebellar peduncle = efferent
- middle cerebellar peduncle = afferent
- inferior cerebellar peduncle = afferent
Where does information go from and to in the inferior cerebellar peduncle? What is the name of this tract?
- from: spinal cord and medulla (unconscious proprioception)
- to: cerebellum
- spinocerebellar tract
Where does information go from and to in the middle cerebellar peduncle? What is the name of this tract?
- from: cortex
- to pontine nuclei (which project to cerebellum)
- corticopontocerebellar tract
Where does information go from and to in the superior cerebellar peduncle? What is the name of this tract?
- from: cerebellum
- to: midbrain and thalamus
- dentatothalamocortical tract
TRUE or FALSE: dentatothalamocortical tract is ipsilateral
FALSE: contralateral
What are the 3 lobes of the cerebellum?
- anterior lobe
- posterior lobe (incl. tonsil)
- flocculonodular lobe
Describe the cerebellar homunculus innervation.
- midline = core/trunk stability
- lateral = distal body parts
Summarize the basic cerebellar game plan.
- Cb receives input from all levels of NS
- Cb projects it back to motor areas via dee Cb nuclei (GABA)
(disinhibition of thalamus)
What are the afferent tracts of the cerebellar game plan?
- corticopontocerebellar tract
- spinocerebellar tract
- vestibulocerebellar tract
What are the 3 layers of the cerebellar cortex, from outermost to innermost?
- molecular layer (cytoplasm/myelin)
- purkinje cell layer
- granule cell layer (nuclei)
Which type of neuron is the only output neuron of the cerebellar cortex, and sends GABAergic axons to deep cerebellar nuclei?
Purkinje cells
What are the 2 afferent fibers that synapse onto Purkinje cells in the cerebellar game plan? Which tracts do they belong to? excitatory or inhibitory? How do they allow movement?
- climbing fibers (+): olivocerebellar tracts; synapse directly onto molecular layer of cerebellum (PC dendrites) –> PC inhibitory projections to deep cerebellar nuclei –> disinhibition via GABA –> allow movement
- mossy fibers (+): spinocerebellar, corticopontocerebellar, vestibulocerebellar tracts; synapse onto granule cell layer –> onto molecular layer (PC dendrites) –> PC inhibitory projections to deep cerebellar nuclei –> disinhibition via GABA –> allow movement
What are the 3 deep cerebellar nuclei?
- fastigial nucleus
- interposed nucleus (incl. globose and emboliform nuclei)
- dentate nucleus
Which nucleus innervates balance and posture? Is it vermal, paravermal, or lateral?
- fastigial nucleus
- vermal
Which nucleus innervates should, hip proximal limb mm? Is it vermal, paravermal, or lateral?
- interposed nucleus (globose and emboliform)
- paravermal
Which nucleus innervates distal limb mm. (motor planning and evaluation of sensory info)? Is it vermal, paravermal, or lateral?
- dentate nucleus
- lateral
Which nucleus in the cerebellar game plan is located in the flocculonodular lobe?
vestibular nuclei
Which tracts are associated with the fastigial nucleus?
- vestibulospinal
- reticulospinal
Which tracts are associated with the interposed nucleus?
- CST (corticospinal)
- CBT (corticobulbar)
- RBS (rubrospinal)
Which parts of the brain are associated with the dentate nucleus?
- ventral anterior/lateral thalamus to motor cortex (dentatothalamocortical tract)
- premotor suppl. motor cortex (CST/CBT)
What is the major cerebellar efferent pathway?
dentatothalamocortical tract
In summary, what does the floccundular lobe of the cerebellum control?
equilibrium and balance
In summary, what does the vermal/paravermal lobe of the cerebellum control?
posture and muscle tone
In summary, what does the lateral lobe/zone of the cerebellum control?
smooth purposeful movements
What is the rubrospinal tract’s function?
excite arm flexors and inhibit arm extensors
