Cerebellum

Question 1

What is unique about the cerebellum?

Answer 1

Receives sensory input but does not discriminate
Lesion rarely results in lasting muscle paralysis
Has component of motor/procedural learning

Question 2

What does the cerebellum do?

Answer 2

Coordinate movements, maintain posture, motor learning/procedural memory

Question 3

What indirect motor tracts does the cerebellum influence?

Answer 3

Tectospinal, vestibulospinal, reticulospinal, rubrospinal

Question 4

What are the deep cerebellar nuclei?

Answer 4

Dentate
Emboliform
Globos
Fastigial

Question 5

What are the layers of gray matter and the cell types found within?

Answer 5

Molecular layer - basket and stellate cells
Purkinje layer - purkinje cells
Granular layer - granule and golgi cells

Question 6

What do purkinje cells do?

Answer 6

Efferents - major output from cerebellar cortex to different nuclei. Inhibit deep cerebellar nuclei and vestibular nuclei via GABA

Question 7

What do granule cells do?

Answer 7

Only excitatory neurons (glutamate), found in granule layer

Question 8

What do golgi cells do?

Answer 8

Inhibitory neurons (GABA), found in granule layer

Question 9

What do stellate cells do?

Answer 9

Synapse only with purkinje cells and inhibit them, found in molecular layer

Question 10

What do basket cells do?

Answer 10

Synapse with purkinje cells and inhibit them (GABA), found in molecular layer

Question 11

What are mossy fibers?

Answer 11

Come from SC, RF, vestibular system, and pontine nuclei to excite granule cells and deep cerebellar nuclei. Convey somatosensory, arousal, equilibrium, and cerebral cortex motor info

Question 12

What are climbing fibers?

Answer 12

Come from inferior olive (in medulla) to excite purkinje cells and deep cerebellar nuclei. Convey movement errors to cerebellum

Question 13

What are the functional divisions of the cerebellum?

Answer 13

Vestibulocerebellum, spinocerebellum, pontocerebellum/cerebrocerebellum

Question 14

What is the vestibulocerebellum?

Answer 14

Flocculonodular lobe + nodulus, receives info from vestibular receptors and visual areas, sends output to vestibular nuclei via purkinje cells that bypass deep cerebellar nuclei. Influences eye movements and balance/equilibrium

Question 15

What is the spinocerebellum?

Answer 15

Vermis + paravermal region. Receives somatosensory info from spinal interneurons and sensorimotor cortex, output to medial UMNs and lateral UMNs for gait

Question 16

What is the pontocerebellum?

Answer 16

Lateral hemispheres of cerebellum, also known as cerebrocerebellum. Input from cerebrum (premotor, sensorimotor) via pontine nuclei. Coordinates voluntary movements (planning and timing)

Question 17

What are the globos nuclei and emboliform nuclei called?

Answer 17

Interposed

Question 18

What is the big picture of input to the cerebellum?

Answer 18

Afferents –> cerebral peduncles –> three functional divisions of cerebellum –> purkinje cells (efferents) –> four deep cerebellar nuclei –> second set of efferents –> targets

Question 19

What afferent fibers go to the cerebellum from the vestibular system?

Answer 19

Vestibular nuclei and CN VIII. Mossy fibers via inferior cerebellar peduncle

Question 20

What afferent fibers go to the cerebellum from the SC?

Answer 20

Posterior spinocerebellar tract (legs) and cuneocerebellar tract (arms)
Also anterior spinocerebellar tract (legs) less important. Mossy fibers via inferior cerebellar peduncle

Question 21

What afferent fibers go to the cerebellum from the cerebral cortex?

Answer 21

Cortico-pontocerebellar and cortico-reticulocerebellar (mossy fibers via middle cerebellar peduncle)
Cortico-olivocerebellar (climbing fibers via middle cerebellar peduncle)

Question 22

What is the pathway of the posterior spinocerebellar tract?

Answer 22

Primary afferent cell body in DRG, travels up in gracile fasiculus until synapsing in Clark’s nucleus (C8-L2) if lower down. Secondary neuron in Clark’s nucleus travels in posterior spinal tract until reaching inferior cerebellar peduncle (restiform body) to get to cerebellum

Question 23

What is the pathway of the cuneocerebellar tract?

Answer 23

Primary afferent cell body in DRG, travels up in cuneate fasiculus to lower medulla to synapse on accessory cuneate nucleus. Secondary neuron cell body in accessory cuneate nucleus, travels up to inferior cerebellar peduncle (restiform body)

Question 24

Where do afferent fibers coming from vestibular system enter the cerebellum?

Answer 24

Juxtarestiform body in inferior cerebellar peduncle

Question 25

What makes up inferior cerebellar peduncle?

Answer 25

Juxtarestiform body and restiform body

Question 26

What fibers do the superior cerebellar peduncles carry?

Answer 26

Efferents from globose, emboliform, and dentate nuclei. Afferents from anterior spinocerebellar tract (tract that crosses twice)

Question 27

What fibers do the middle cerebellar peduncles carry?

Answer 27

Afferents from pontine nuclei relayed to cortex

Question 28

What fibers do the inferior cerebellar peduncles carry?

Answer 28

Afferents from spinal cord

Question 29

Where does the fastigial nucleus communicate with?

Answer 29

Vestibular nucleus and reticular formation

Question 30

Explain how the fastigial nucleus communicates with the vestibular nuclei

Answer 30

Fastigial nucleus sends fibers to vestibular nucleus which sends fibers to vestibulospinal tract

Question 31

Explain how the fastigial nucleus communicates with the reticular formation

Answer 31

Fastigial nucleus sends fibers to pontine reticular formation and medullary reticular formation which sends fibers down reticulospinal tracts to affect posture

Question 32

Where does the dentate nucleus communicate with?

Answer 32

Red nucleus and thalamus (VL)

Question 33

Explain how the dentate nucleus communicates with the thalamus

Answer 33

Leaves via superior cerebellar peduncle. Goes to VL of thalamus which sends fibers to motor cortex. Can also go to red nucleus in midbrain which affects rubrospinal tract for flexion of upper limbs

Question 34

Where do interposed nuclei communicate with?

Answer 34

Red nucleus and thalamus (VL)

Question 35

What system helps in correction of motor errors?

Answer 35

Anything that runs from cortex to olive to cerebellum

Question 36

Unilateral lesion of cerebellum results in deficits where?

Answer 36

Ipsilateral side motor issues and ataxia w/ wide-base gait and pt falhe ling to side of lesion when walking

Question 37

What does a lesion to the vestibulocerebellum do?

Answer 37

Eye movements, balance, and equilibirum problems. -Nystagmus, truncal ataxia (difficulty maintaining sitting/standing), truncal instability (titubation - shaking back and forth), and problems w/ tandem walking (midline ataxia)

Question 38

What does a lesion of the spinocerebellum do?

Answer 38

Wide-based gait and difficulty tandem walking (midlilne ataxia)

Question 39

What does a lesion of the cerebrocerebellum do?

Answer 39

Dysarthria, ataxic gait (staggering), decomposition of movements/speech, dysdiadochokinesia (inability to rapidly alternate movements), dysmetria (inability to accurately move intended distance), and action tremor (shaking of limb during voluntary movement)

Question 40

What is midline ataxia vs appendicular ataxia?

Answer 40

Midline - damage to vestibulocerebellar and spinocerebellar areas. Truncal instability and gait ataxia
Appendicular - damage to cerebrocerebellum. Problems with limbs, ataxia of speech, decomposition of movement, dysmetria, dysdiadochokinesia

Question 41

What is cerebellar ataxia?

Answer 41

Damage to cerebellum. Positive romberg test (cannot stand with feet together with eyes open or shut). Normal vibratory sense, proprioception, and ankle reflexes

Question 42

What is sensory ataxia?

Answer 42

Damage to dorsal columns. Positive romberg test (but can stand with feet together with eyes open). Abnormal vibratory sense, proprioception, and ankl reflexes