Cerebellum and Motor Control Flashcards
what does cerebellum mean?
“little brain”
what similarities does the cerebellum share with the cerebrum?
- Two hemispheres
- Outer cortical layer of gray matter
(cerebellar cortex) and inner region
of white matter and subcortical nuclei (deep cerebellar nuclei)
does the cerebrum or cerebellum contain more neurons?
the cerebellum has 4x as many neurons as the cerebrum
True or false: efferents project directly
to local circuits or LMNs?
false
is the cerebellum responsible for initiating movement?
no
how does the cerebellum primarily operate?
by modifying the activity of UMNs
how does the cerebellum modify the activity of UMNs?
Adjusts the motor activity of
the descending pathways to
make movements more accurate
list the cortical layers of the cerebellum from deepest to most superficial
granule - purkinje - molecular
what is the deep lateral nucleus of the cerebellum?
dentate nucleus
what are the 3 medial nuclei of the deep cerebellum?
2 interposed nuclei
1 fastigial nucleus
what is the honorary nucleus of the deep cerebellum?
vestibular nuclei
does the cerebellum have a homunculus?
yes
what is the somatotopic organization of the cerebellum?
- Axial muscles represented more centrally
- Distal muscles represented more laterally
what are the functional divisions of the cerebellum?
- Vestibulocerebellum
- spinocerebellum
- cerebrocerebellum
what is the function of the vestibulocerebellum?
postural control
what is the function of the spinocerebellum?
gross movements of the trunk and limbs
what is the function of the cerebrocerebellum?
fine motor voluntary movements
what are the cerebellar preduncles?
Connections between cerebellum and other
parts of the CNS
is the superior preduncle efferent or afferent?
exclusively efferent
is the middle preduncle efferent or afferent?
exclusively afferent
is the inferior preduncle efferent or afferent?
both
where do efferents from the superior preduncle go to?
thalamus and superior colliculus
where do afferents from the middle preduncle come from?
pontine nuclei
where do afferents from the inferior preduncle come from?
vestibular nuclei, spinal cord, brainstem
where do efferents from the inferior preduncle go to?
vestibular nuclei and reticular formatio
what is the role of the vestibulocerebellum?
- Integrates vestibular information from vestibular apparatus in inner ear and vestibular nuclei
- Provides information on head position with
respect to gravity - Receives visual information from visual cortex
- Modifies vestibular reflexes for eye movements (ie. VOR) and postural control
what tracts does the vestibulocerebellum influence?
vestibulospinal tracts
where does the spinocerebellum receive information from?
spinal cord, vestibular nuclei, and
brainstem nuclei
what is the vermis of the spinocerebellum responsible for?
balance and proximal motor control
what is the paravermis of the spinocerebellum responsible for?
distal motor control
what does output from the spinocerebellum include?
motor cortex via thalamus and extrapyramidal and pyramidal tracts for motor execution
what does the vermal part of the spinocerebellum influence?
vestibulospinal tracts
where is input to the cerebrocerebellum from?
cerebral cortex
what is the function of the cerebrocerebellum?
Planning and timing of highly skilled
distal movements
what does the cerebrocerebellum form a closed loop with?
the cerebral cortex
what does output from the cerebrocerebellum include?
cerebral cortex and lateral corticospinal and corticobulbar tracts
what are the main functions of the cerebellum?
- Planning and execution of movement
- Coordination of multi-jointed movement
- Postural control
- Error correction
are clinical signs of cerebellar lesions are typically ipsilateral or contralateral to the lesion?
ipsilateral
what is ataxia?
incoordination of movement
what else can a cerebellar lesion cause?
- Poor postural control
- Difficulty learning highly skilled sequences
what are signs of Vestibulocerebellum damage?
- Spontaneous nystagmus
- Postural instability
- Truncal ataxia
what are signs of Spinocerebellum damage?
- Damage to vermis
* Truncal ataxia - Damage to paravermis
* Dysarthria
* Limb ataxia (dysdiadochokinesia, dysmetria,
intention tremor)
* Ataxic gait
what are signs of Cerebrocerebellar damage?
- Loss of coordination of fine finger movements
- Dysarthria
what is intention tremor?
Tremor during movement
Increases as reach target
what is dysmetria?
- Overshooting or undershooting
as limb approaches a target - Inability to gauge the distance
what is Dysdiadochokinesia?
Difficulty performing rapid alternating movements
what is a special test for dysmetria?
heel to shin test
what is the definition of motor control?
The ability to regulate or direct the
mechanisms essential to movement
what information does normal motor control rely heavily on?
visual
somatosensory
vestibular
what brain structures are heavily involved in motor control?
basal ganglia and cerebellum
what are the 3 main types of upper extremity impairments?
- Perceptual problems
- Reach and grasp impairments
- Grasp and in-hand manipulation impairments
what can perceptual problems be caused by?
visual field deficits, neglect, and agnosia
- Difficulty locating target
- Object identification (visual agnosia)
- Difficulty planning and executing reach and grasp
what is the Largest contributor to impaired reaching post- stroke?
loss of individuation
what are abnormal synergies?
Obligatory co-activation of muscles during
voluntary motion
what does loss of individuation typically affect?
flexors of the upper extremities and extensors of the lower extremities
