Cerebellum and Motor Control

Question 1

what does cerebellum mean?

Answer 1

“little brain”

Question 2

what similarities does the cerebellum share with the cerebrum?

Answer 2

• Two hemispheres
• Outer cortical layer of gray matter
  (cerebellar cortex) and inner region
  of white matter and subcortical nuclei (deep cerebellar nuclei)

Question 3

does the cerebrum or cerebellum contain more neurons?

Answer 3

the cerebellum has 4x as many neurons as the cerebrum

Question 4

True or false: efferents project directly
to local circuits or LMNs?

Answer 4

false

Question 5

is the cerebellum responsible for initiating movement?

Answer 5

no

Question 6

how does the cerebellum primarily operate?

Answer 6

by modifying the activity of UMNs

Question 7

how does the cerebellum modify the activity of UMNs?

Answer 7

Adjusts the motor activity of
the descending pathways to
make movements more accurate

Question 8

list the cortical layers of the cerebellum from deepest to most superficial

Answer 8

granule - purkinje - molecular

Question 9

what is the deep lateral nucleus of the cerebellum?

Answer 9

dentate nucleus

Question 10

what are the 3 medial nuclei of the deep cerebellum?

Answer 10

2 interposed nuclei
1 fastigial nucleus

Question 11

what is the honorary nucleus of the deep cerebellum?

Answer 11

vestibular nuclei

Question 12

does the cerebellum have a homunculus?

Answer 12

yes

Question 13

what is the somatotopic organization of the cerebellum?

Answer 13

• Axial muscles represented more centrally
• Distal muscles represented more laterally

Question 14

what are the functional divisions of the cerebellum?

Answer 14

1. Vestibulocerebellum
2. spinocerebellum
3. cerebrocerebellum

Question 15

what is the function of the vestibulocerebellum?

Answer 15

postural control

Question 16

what is the function of the spinocerebellum?

Answer 16

gross movements of the trunk and limbs

Question 17

what is the function of the cerebrocerebellum?

Answer 17

fine motor voluntary movements

Question 18

what are the cerebellar preduncles?

Answer 18

Connections between cerebellum and other
parts of the CNS

Question 19

is the superior preduncle efferent or afferent?

Answer 19

exclusively efferent

Question 20

is the middle preduncle efferent or afferent?

Answer 20

exclusively afferent

Question 21

is the inferior preduncle efferent or afferent?

Answer 21

both

Question 22

where do efferents from the superior preduncle go to?

Answer 22

thalamus and superior colliculus

Question 23

where do afferents from the middle preduncle come from?

Answer 23

pontine nuclei

Question 24

where do afferents from the inferior preduncle come from?

Answer 24

vestibular nuclei, spinal cord, brainstem

Question 25

where do efferents from the inferior preduncle go to?

Answer 25

vestibular nuclei and reticular formatio

Question 26

what is the role of the vestibulocerebellum?

Answer 26

* 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

Question 27

what tracts does the vestibulocerebellum influence?

Answer 27

vestibulospinal tracts

Question 28

where does the spinocerebellum receive information from?

Answer 28

spinal cord, vestibular nuclei, and brainstem nuclei

Question 29

what is the vermis of the spinocerebellum responsible for?

Answer 29

balance and proximal motor control

Question 30

what is the paravermis of the spinocerebellum responsible for?

Answer 30

distal motor control

Question 31

what does output from the spinocerebellum include?

Answer 31

motor cortex via thalamus and extrapyramidal and pyramidal tracts for motor execution

Question 32

what does the vermal part of the spinocerebellum influence?

Answer 32

vestibulospinal tracts

Question 33

where is input to the cerebrocerebellum from?

Answer 33

cerebral cortex

Question 34

what is the function of the cerebrocerebellum?

Answer 34

Planning and timing of highly skilled distal movements

Question 35

what does the cerebrocerebellum form a closed loop with?

Answer 35

the cerebral cortex

Question 36

what does output from the cerebrocerebellum include?

Answer 36

cerebral cortex and lateral corticospinal and corticobulbar tracts

Question 37

what are the main functions of the cerebellum?

Answer 37

* Planning and execution of movement * Coordination of multi-jointed movement * Postural control * Error correction

Question 38

are clinical signs of cerebellar lesions are typically ipsilateral or contralateral to the lesion?

Answer 38

ipsilateral

Question 39

what is ataxia?

Answer 39

incoordination of movement

Question 40

what else can a cerebellar lesion cause?

Answer 40

* Poor postural control * Difficulty learning highly skilled sequences

Question 41

what are signs of Vestibulocerebellum damage?

Answer 41

* Spontaneous nystagmus * Postural instability * Truncal ataxia

Question 42

what are signs of Spinocerebellum damage?

Answer 42

* Damage to vermis * Truncal ataxia * Damage to paravermis * Dysarthria * Limb ataxia (dysdiadochokinesia, dysmetria, intention tremor) * Ataxic gait

Question 43

what are signs of Cerebrocerebellar damage?

Answer 43

* Loss of coordination of fine finger movements * Dysarthria

Question 44

what is intention tremor?

Answer 44

Tremor during movement Increases as reach target

Question 45

what is dysmetria?

Answer 45

* Overshooting or undershooting as limb approaches a target * Inability to gauge the distance

Question 46

what is Dysdiadochokinesia?

Answer 46

Difficulty performing rapid alternating movements

Question 47

what is a special test for dysmetria?

Answer 47

heel to shin test

Question 48

what is the definition of motor control?

Answer 48

The ability to regulate or direct the mechanisms essential to movement

Question 49

what information does normal motor control rely heavily on?

Answer 49

visual somatosensory vestibular

Question 50

what brain structures are heavily involved in motor control?

Answer 50

basal ganglia and cerebellum

Question 51

what are the 3 main types of upper extremity impairments?

Answer 51

1. Perceptual problems 2. Reach and grasp impairments 3. Grasp and in-hand manipulation impairments

Question 52

what can perceptual problems be caused by?

Answer 52

visual field deficits, neglect, and agnosia * Difficulty locating target * Object identification (visual agnosia) * Difficulty planning and executing reach and grasp

Question 53

what is the Largest contributor to impaired reaching post- stroke?

Answer 53

loss of individuation

Question 54

what are abnormal synergies?

Answer 54

Obligatory co-activation of muscles during voluntary motion

Question 55

what does loss of individuation typically affect?

Answer 55

flexors of the upper extremities and extensors of the lower extremities