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Neuro Final Exam > Cerebellum > Flashcards

Cerebellum Flashcards

1
Q

Function(s) of the Cerebellum

A
  1. Coordinate movements
  2. Maintain posture
  3. Motor learning (procedural memory)

receives a lot of sensory input, but does not interpret it
lesions do not cause lasting motor paralysis - it causes motor DYSFUNCTION

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2
Q

Organization of Gray Matter in the Cerebellum

A
  1. Molecular Layer - next to pial surface; few neurons; cell bodies of basket and stellate cells
  2. Purkinje Layer - Purkinje cell bodies
  3. Granular Layer - deepest layer; granule cells and a few Golgi cells
  4. White Matter - neuronal axons

be familiar with histological images

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3
Q

Purkinje Cells

A

EFFERENTS
output cells from the cerebellar cortex
- inhibits cerebellar nuclei and the vestibular nuclei (GABA)
highly differentiated, many dendrites

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4
Q

Granule Cells

A

Smallest neurons, only excitatory neurons, NT is glutamate

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5
Q

Stellate Cells

A

axons synapse with Purkinje cells and inhibit them; star-shaped dendrites

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6
Q

Golgi Cells

A

Inhibitory; NT is GABA, large/scattered neurons with short axons

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7
Q

Basket Cells

A

axons synapse with Purkinje cells and inhibit them; NT is GABA

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8
Q

Name the two types of afferent fibers

A

1: Climbing Fibers
2: Mossy Fibers

Both are excitatory fibers; send collaterals to the deep cerebellar nuclei in addition to their respective synapses

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9
Q

Name the deep cerebellar nuclei

A
  1. emboliform nucleus
  2. dentate nucleus
  3. globose nucleus
  4. fastigial nucleus
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10
Q

Climbing Fibers

A
  • Afferent fibers
  • From the inferior olive in the medulla
  • Myelinated, excitatory influence on Purkinje cells
  • Convey info about movement errors to the cerebellum
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11
Q

Mossy Fibers

A
  • Afferent fibers
  • From SC, reticular formation, vestibular system, and pontine nucleir (everywhere but inferior olive)
  • Synapse w/ granulocytes in granular layer
  • Somatosensory, arousal, equilibrium, and cerebral cortex motor info to cerebellum
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12
Q

Vestibulocerebellum

A
  • Functional name for flocculonodular lobe
  • Receives info from vestibular receptors (CN VIII and vestibular nuclei), also from visual areas
  • Send output to vestibular nuclei
  • FXN: influence eye movements and postural muscles of the head and body
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13
Q

Spinocerebellum

A
  • Functional name for vermis and paravermal region
  • Somatosensory info, internal feedback from spinal interneurons and sensorimotor cortex
  • FXN: control ongoing movement via brainstem descending tracts
  • Vermis control postural muscles
  • Paravermis controls UMNs (move limbs, gait and station)
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14
Q

Ponto/Cerebrocerebellum

A
  • Input from cerebral cortex via the pontine nuclei
  • FXN: coordination of voluntary movements, planning of movements, and timing
  • coordinates fine movements for fractionation*
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15
Q

From where does the cerebrocerebellum receive afferent fibers?

A

From the cerebral cortex:

  • Mossy fibers from the cortico-pontocerebellar and cortico-reticulocerebeller
  • Climbing fibers from the cortico-olivocerebellar
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16
Q

From where does the spinocerebellum receive afferent fibers?

A

From the spinal cord:

-Mossy fibers form the anterior/posterior spinocerebellar tracts and the cuneocerebellar tract

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17
Q

From where does the vestibulocerebellum receive afferent fibers?

A

From the vestibular system:

-Mossy fibers from the vestibular nuclei and CN VIII

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18
Q

What information is carried by the afferent fiber pathways?

A

unconcsious proprioception about limb movement

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19
Q

Describe the posterior spinocerebellar tract

A

SC afferent fiber pathway

  • axons carrying unconscious proprioception from lower limb
  • 1st order neuron enters via the dorsal root ganglion
  • ascends in gracile fasiculus
  • synapse in nucleus dorsalis of Clark (gray matter from C8-L2)
  • 2nd order neuron ascends in dorsolateral funiculus
  • enters the cerebellum bia the inferior cerebellar peduncle
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20
Q

Describe the cuneocerebellar tract

A

SC afferent fiber pathway

  • axons carrying unconscious proprioception from upper limb
  • 1st order neuron enters via the dorsal root ganglion
  • ascends in the cuneate fasiculus
  • synapses in accessory/lateral/external cuneate nucleus in the lower medulla
  • 2nd order neuron from the accessory cuneate nuscleus ascends to the cerebellum
  • enters via the inferior cerebellar nucleus
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21
Q

Big picture information about the anterior spinocerebellar tract

A
  • carries unconscious proprioception from the lower extremity; also Pacinian/Meissner/Meckel corpuscle
  • CROSSES 2X (in the anterior white commissure and after entering the superior cerebellar peduncle)
22
Q

Superior Cerebellar Peduncle

A
  • major efferent for globose, emboliform, and dentate nuclei

- afferent fibers from the ventral spinocerebellar tract

23
Q

Middle Cerebellar Peduncle

A
  • largest peduncle
  • in the area of the pons
  • relays afferent fibers from pontine nuclei to cortex
24
Q

Inferior Cerebellar Peduncle

A

Main afferent pathway from SC

25
Q

Function of Vestibulocerebellum

A

Eye movements and neck/trunk movements

26
Q

Function of Spinocerebellum

A

axial/lower extremity movements, gait, station

27
Q

Function of Cerebrocerebellum

A

precise/coordinated movements of extremities (mainly the upper extremity)

28
Q

Cerebrocerebellum transmits to:

A
  • Dentate nucleus

- Some globose/emboliform (interposed) nuclei

29
Q

Spinocerebellum transmits to:

A
  • Globose/Emboliform (interposed) nuclei (paravermal region sends info here)
  • Fastigial nucleus (info from the vermis)
  • Dentate nucleus
30
Q

Vestibulocerebellum transmits to:

A
  • Vestibular nucleus (bypasses the deep cerebellar peduncle; takes the inferior cerebellar peduncle and leaves via the juxtarestiform body)
  • Some fastigial nucleus
31
Q

Dentate Nucleus targets:

A

red nucleus, thalamus, VL of thalamus

32
Q

Interposed nuclei targets:

A

red nucleus, thalamus, VL of thalamus

33
Q

Fastigial nucleus targets:

A

reticular formation and vestibular nucleus

34
Q

Describe the effect of unilateral cerebellar lesions, and explain the mechanism of the effect

A

Unilateral lesions affect the ipsilateral side

-crosses to the opposite red nucleus, but crosses again when going back down

35
Q

Common sign of cerebellar lesions

A

Ataxia

  • voluntary, normal strength, jerky, and inaccurate movements
  • not associated with hyperstiffness
  • wide base gait, stumble
  • when damage is unilateral, fall to side of lesion
36
Q

Describe lesions of vestibulocerebellum

A
  • between vestibular system and flocculonodular lobe
  • nystagmus*
  • truncal ataxia
  • truncle instability (titubation)
37
Q

What is truncal ataxia?

A

difficulty maintaining sitting and standing balance

38
Q

What is truncal instability/titubation?

A

Anterior-posterior tremor, can’t tandem walk (sobriety test)

39
Q

Describe lesions of spinocerebellum

A
  • between cutaneous/proprioceptive info from SC to the vermis/paravermal regions
  • gait and truncal ataxia (wide, staggering base)
40
Q

Describe midline ataxia

A

Caused by vestibulocerebellar and spinocerebellar disease

  • truncal instability (titubation and gait ataxia)
  • equilibratory (gait) ataxias
41
Q

What is gait ataxia?

A

wide based, irregular steps with lateral veering (toward side of lesion)

42
Q

What is dysarthria?

A

slurred, poorly articulated speech
-scanning speech: spoken words are broken up into separate syllables, often separated by a notable pause, spoken w/ varying force

43
Q

What is movement decomposition?

A

movements are broken up into their individual compents

44
Q

Describe dysdiadochokinesia?

A

inability to rapidly alternate your movements

45
Q

Describe dysmetria?

A

inability to accurately move an intended distance

46
Q

Describe action tremors/intention tremors

A
  • shaking of limb during voluntary movement

- tremor worsens as a patient tries to touch their target (worse at the end of the movement)

47
Q

Describe cerebroserebellum lesions

A
  • lateral hemispheres of the cerebellum

- dysarthria, ataxic gait, decomposition of movements, limb ataxia (dysdiadochokinesia, dysmetria, action tremors)

48
Q

Describe appendicular ataxia

A
  • dysfunction of the cerebellar hemispheres that results in ataxia of the extremities
  • also ataxia of speech (scanning dysarthria)
  • hypotonia, decomposition of movement, dysmetria, dysdiadochokinesia
49
Q

How can you differentiate between cerebellar ataxia and sensory ataxia?

A

Cerebellar ataxia: normal vibratory sense, proprioception, and ankle reflexes
Sensory ataxia: abnormal vibratory sense, proprioception, and ankle reflexes; can stand with feet together when eyes are open

50
Q

Describe cerebellar ataxia

A

Positive Romberg test (unable to stand with their feet together), normal vibratory sense/proprioception/ankle reflexes

51
Q

Describe sensory ataxia

A

Positive Romberg test when eyes are closed (can stand with feet together when eyes are open), abnormal vibratory sense/proprioception/ankle reflexeS

52
Q

Tests to run to examine the cerebellum

A

Vestibulocerebellum and Spinocerebellm:

  • station
  • walking
  • tandem gait

Cerebrocerebellum:

  • rapid alternating movements
  • finger-to-nose/toe-to-finger
  • heel-to-shin
  • rebound and check reflex
  • speech

Neuro Final Exam (14 decks)

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