Cerebellum

Question 1

Function of the Cerebellum

Answer 1

• coordinates movement by influencing timing and force of contractions of voluntary muscles
• involved in motor planning and motor learning
• adjusts posture
• Plays a role in eye movements, balance, locomotion, learning

Compares actual motor output w/ intended movement (from frontal lobe) and then adjusts as necessary

Question 2

What does the cerebellum not do

Answer 2

• is not primary in sensory function
• with damage one can still feel
• is not primary in motor function
• with damage one is not paralyzed or weak

Question 3

Integration in the cerebellum

Answer 3

once information arrives at the cerebellum

• sent to the cerebellar cortex
• cerebellar cortex sends input to deep cerebellar nuclei
• information sent back out to affect CNS and periphery
• information coming to the cerebellum includes that coming from the cerebral cortex

Question 4

Inputs to the cerebellum

Answer 4

• Cerebral cortex => pontine nuclei on contralateral side
• vestibular system ispilaterally
• spinal cord ipsilaterally
• proprioceptors (to SC) ipsilaterally

Question 5

Outputs from the cerebellum

Answer 5

• brainstem
• spinal cord
• cerebral cortex
• red nucleus (midbrain)
• thalamus

cerebral output is vital for normal movement
projections to thalamus are motor these outputs then project to motor areas of cerebral cortex

Question 6

What is the rule of three in the cerebellum

Answer 6

• three lobes
• three vertical sections
• three layers of the cerebullar cortex
• three functional movement divisions
• three pairs of deep nuceli
• three pairs of peduncles

Question 7

What are the three lobes of the cerebellum

Answer 7

• anterior
• posterior
• flocculonodular lobe

Question 8

anterior lobe

Answer 8

• superiorly
• seperated from posterior lobe by primary fissue

Question 9

Posterior lobe

Answer 9

• inferior
• cerebellar tonsils
• clinically = increased intracranial pressure can force tonsils into foramen magnum
• therefore compressing vital brainstem structures that regulate breathing and cardiovascular activty

Question 10

flocculonodular lobe

Answer 10

• tucked under posterior lobe

Question 11

3 vertical sections of the cerebellum

Answer 11

• midline vermis: medial
• intermediate zone of paravermis
• lateral hemisphere

Question 12

Vertical section

midline vermis:

Answer 12

• medial
• posture and trunk ataxia
• eye movement abnormalities
• accompanies by vertigo nausea and vomitin

when lesion occurs

Question 13

vertical sections

intermediate zone of paravermis

Answer 13

• proprioceptive sensory information to correct movement error

Question 14

vertical sections

lateral hemisphere

Answer 14

• limb control ataxia

Question 15

What are the functional movement divisions

Answer 15

1. Vestibulocerebeullum: regulates equilibrium, balance and eye movement
2. Spinocerebellum: coordinates gross limb movement
3. Cerebrocerebellum: coordinates precise, distal voluntary movement

Question 16

3 layers of the cerebellar cortex

Answer 16

1. outer neurons: inhibitory
2. purkinje cell bodies: inhibitory damage = disinhibition of movement
3. inner: interneurons, mossy fibers, climbing fibers

Question 17

Mossy fibers

Answer 17

• input fibers
• originate in spinal cord and brainstem
• convey somatosensory arousal, equilibrium and cerebral cortex information to cerebellum
• stimulate release of cortical motor pathways

Question 18

Climbing fibers

Answer 18

• input fibers
• from inferior olivary nucleus in medulla
• conveys information reguarding movement error to cerebellum,
• active in learning new movement (excitatory)

Question 19

3 pairs of deep cerebellar nuclei

Answer 19

• main influence on other motor centers
• receive excitatory input from mossy and climbing fibers
• receive inhibitory input from purkinje cells
• Types medial to lateral: Fastigial, interposed (globose and emboliform), and dentate
• each vertical section projects to specific cerebellar nuceli or vestibular nuceli

Question 20

Fastigal nuclei

Answer 20

• part of vestiularcerebellum (regulates equilibrium
• ex: reaching to a high shlef; provides anticipatory contraction of the LE and back muscles to prevent balacne loss
• sends information to vestibular nuclei
• important for balance and eye movement

Question 21

Interposed nuclei

Answer 21

• part of spinocerebellum - coordinates gross limb movement
• sends information to reticular formation red nucleus and thalamus
• motor learning/planning and limb movements

Question 22

Dentate nucleus

Answer 22

• part of cerebrocerebellum - coordinates distal limb movements
• sends information to motor and premotor cortex
• motor planning and locomotion

Question 23

Cerebellar peduncles

Answer 23

carry information between cerebellum and brainstem

• inferior cerebellar peduncle: from medulla (afferenet and efferent)
• middle cerebellar peduncle: from pons (afferent only)
• superior cerebellar peduncle: from midbrain, efferent only

Question 24

Integration of motor and sensory information

Answer 24

• cerebellum gets input and sends information from contralateral cortex and ispilateral body
• cerebellar stroke: unilateral lesions affect SAME side of body
• coordination of voluntary movement via influence on corticospinal and cotricobranstem tracts

Question 25

Causes of cerebellar damage

Answer 25

- cerebral vascular accident - multiple sclerosis - tumor - trauma - degnerative disease - alcoholism (anterior lobe)

Question 26

Cerebellar damage

Answer 26

- impacts voluntary coordinated movement - rate - range - force

Question 27

Common signs of cerebellar damage

Answer 27

- ataxia - dysmetria: inability to accurately move intended distance - dysdiadochokinesia: inability to rapidly alternate movements - hypotonia - intention tremor - postural instability and gait disturbance - dysarthria

Question 28

# effects of cerebellar damage on locomotion

Answer 28

- increased postural sway - excessive or diminished responses to pertubrations - abnormal oscillations of the trunk - gait ataxia - decomposition of movement: maintaining a fixed position of one joint while other is moving *decreased smoothness*

Question 29

# effects of damage to vestibulocerebellum on locomation

Answer 29

- head tilt - horizontal nystagmus: eye "twitiches" horizontally - circling away from and falling toward side of lesion - gait ataxia

Question 30

# effects of damage to posterior vermis on locomotion

Answer 30

- common cause: tumor in fourth ventricle - gait ataxia without limb ataxia - marked deficit in tandem gait - may be able to reach, kick, and perform unilateral stance

Question 31

# effects of damage to anterior lobe on locomotion

Answer 31

- common cause: atrophy due to alcoholism - begins in anterior vermis and intermediate portions of anterior lobe - gait ataxia - unable to preform unilateral stance - ataxia with heel-to-shin test - deficits in reaching and speech as disease progresses posteriorly

Question 32

Cerebellum and medial lesions vs lateral

Answer 32

- somatotrophic representation - medial lesions: dizziness and eye movemetns - lateral = limbs

Question 33

Pathology of anterior lobe

Answer 33

- multiple sclerosis - friedreich's ataxia: hereditary spinal ataxia

Question 34

cerebellar disorders

Answer 34

- paraneoplastic syndrome: somthing that looks like cerebellum in nature but there is actually a dormit cancer that could develop – often lung cancer - arnold chiari malformation