The Cerebellum

Front 1

What is the primary sign of cerebellar dysfunction?

Back 1

Ataxia

Front 2

How is ataxia manifested?

Back 2

Inaccuracies of placement of limbs (dysmetria) or by defects in timing or patterning of muscle contractions

Front 3

What are the conduits for all input and output in the cerebellum?

Back 3

3 pairs of cerebral peduncles

Front 4

What are inputs to the cerebellum?

Back 4

Sensory information from throughout the body and from brainstem and cortex

Front 5

How is input carried into the cerebellum?

Back 5

Mossy and climbing fibers

Front 6

How is output carried out of the cerebellum?

Back 6

Deep cerebellar nuclei projecting to motor centers in brainstem and cortex (no direct projections to motoneurons)

Front 7

What is the gross cerebellar circuit?

Back 7

Cortex sends information to the dorsal column nuclei through Purkinje cells which are inhibitory; DCN project to motor systems, which project to motoneurons

Front 8

The most severe cerebellar signs occur when there is damage to what?

Back 8

Either deep cerebellar nuclei or superior cerebellar peduncle, because these transmit most of the efferent fibers leaving the cerebellum

Front 9

Motor disorders are generally ipsi or contralateral to the cerebellar lesion?

Back 9

Ipsilateral, because efferents leaving the cerebellum first decussate at the superior cerebellar peduncle to influence motor systems (i.e. rubrospinal and corticospinal) whose efferent tracts decussate on their path to motoneurons (double cross)

Front 10

What are the 3 subdivisions of the cerebellum?

Back 10

Vestibulo-cerebellum, spino-cerebellum and cerebro-cerebellum

Front 11

The vestibulo-cerebellum is is composed of what?

Back 11

Flocullonodular lobe

Front 12

Input to the vestibulo-cerebellum is via the?

Back 12

Inferior peduncle

Front 13

Output from the vestibulo-cerebellum is via the?

Back 13

Vestibular nuclei

Front 14

The spino-cerebellum is composed of what?

Back 14

Vermis and intermediate zone

Front 15

Input to the spino-cerebellum is via the?

Back 15

Middle and superior peduncles

Front 16

Output from the spino-cerebellum is via the?

Back 16

Fastigial and interposed nuclei

Front 17

The cerebro-cerebellum is composed of what?

Back 17

Lateral hemispheres

Front 18

Input to the cerebro-cerebellum is via the?

Back 18

Middle and superior peduncles

Front 19

Output from the cerebro-cerebellum is via the?

Back 19

Dentate nuclei

Front 20

What are some abnormalities sometimes seen in ataxia?

Back 20

Dysmetria, disdiadochokinesia and decomposition of movement

Front 21

What is dysmetria?

Back 21

Inaccuracy in the placement of limbs (may show action/intention tremor); tested by finger-to-finger

Front 22

What is action/intention tremor?

Back 22

Unsteadiness in approaching a target; not true tremor

Front 23

What is disdiadochokinesis?

Back 23

Inability to perform repetitive tasks; tested by rapidly alternating hand movements

Front 24

What is decomposition of movement (asynergia)?

Back 24

Problems with multi-joint movements; may be able to competently move one joint, but unable to coordinate several

Front 25

What is the apparent cause of ataxia?

Back 25

Discoordinatioin in muscle activity

Front 26

In spino- and cerebro-cerebellar dysfunction, what is the basis of cerebellar ataxia?

Back 26

Delays in both the initiation and termination of muscle activity, causing the limb to overshoot the target.

Front 27

How does dysfunction due to lesions of the spino- and cerebro-cerebellum differ from those due to basal ganglia?

Back 27

There is no change in velocity of movement with lesions of the spino- and cerebro-cerebellum

Front 28

What are some additional motor signs of spino- and cerebro-cerebellar dysfunction?

Back 28

Hypotonia & pendular reflexes and dysarthria

Front 29

What are hypotonia & pendular reflexes?

Back 29

Less-than-normal resistance to passive limb movement resulting from a decreased stretch reflex that causes limb to swing back and forth because of its own mass

Front 30

What is dysarthria?

Back 30

Speech loss or difficulty due to a motor disorder, characterized by slurred speech and sometimes by explosive variations in voice intensity; may exhibit "scanning speech"- multisyllabic words spoken in disjointed fashion with delay between syllables

Front 31

Motor effects due to vestibulo-cerebellar dysfunction resemble what?

Back 31

Virtually indistinguishable from motor effects of injury to vestibular or peripheral vestibular apparatus (ataxia and nystagmus)

Front 32

What are the motor effects of damage to the vestibulo-cerebellum?

Back 32

Ataxic gait and nystagmus; also vertigo; these effects can result from toxic effects of ethanol on flocculonodular lobe

Front 33

What is ataxic gait?

Back 33

Staggering with tendency to fall toward the side of the lesion; reflects inability to coordinate proprioceptive information (body position) with vestibular information (gravity-associated changes in body motion)

Front 34

What is nystagmus?

Back 34

Rhythmic oscillation of the eyes, with the fast phase toward the side of the lesion

Front 35

The vestibulo-cerebellum is involved in what?

Back 35

Balance and eye movement

Front 36

The spino-cerebellum is involved in what?

Back 36

Motor execution

Front 37

The cerebro-cerebellum is involved in what?

Back 37

Motor planning

Front 38

Cerebellar injury has which effects on muscle tone and reflexes?

Back 38

Hypotonia and decreased reflexes

Front 39

Walking has which two requirements?

Back 39

1. An intact vestibular system- ability to locate self in space

2. Control of proximal axial musculature- spinocerebellum

Front 40

What occurs if the vestibular system is knocked out?

Back 40

No balance; can walk with support of trunk

Front 41

What occurs if the spinocerebellum is knocked out?

Back 41

Unable to walk straight, even with support of trunk