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Neuro Exam 3 > 1. Cerebellum > Flashcards

1. Cerebellum Flashcards

1
Q

What are the 3 functions of the cerebellum?

A

1. Coordinates movements

2. Maintains posture

3. Motor learning (procedural memory- riding a bike)

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2
Q

A lesion to the cerebellum will cause: _________

A

Motor dysfunction, not motor paralysis.

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3
Q

How does the cerebellum help coordinate movements and maintain posture?

A

It rec_eives sensory input about the position of our body_, but does not descriminate or interpret it.

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4
Q

The cerebellum consists of two major parts: what are they?

A

1. Cerebellar CTX

2. Deep cerebellar nuclei

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5
Q

What are the deep cerebellar nuclei?

A
  • 1. Fastigial nucleus
  • 2. Dentate nucleus
  • 3. Interposed nucleus (made up of the emboliform nucleus and the globose nucleus).
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6
Q

What are the divisions of the cerebellum?

A

Two fissures running mediolaterally divide the cerebellar cortex into three primary subdivisions: primary fissure and posterolateral fissure.

  • Posterolateral fissure separates the flocculonodular lobe and the posterior lobe.
  • Primary fissure seperates the anterior lobe from the posterior lobe.
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7
Q

How is the gray matter of the cerebellum organized?

A
  1. Molecular layer: has CB of basket cells and stellate cells
  2. Purkinje layer: CB of purkinje cells
  3. Granular layer: granule cells and golgi cells
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8
Q

What are the types of neurons in the gray matter of the cerebellum?

A

1, Purkinje cell

2. Granule cells

3. Stellate cells

4. Golgi cells

5. Basket cells

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9
Q

All neurons in the cerebellum are inhibitory, releasing GABA.

What is the ONLY excitatory neuron?

A
  1. Granule cells, release glutamate.
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10
Q

What are the main output cells (efferents) from the cerebellum

A
  • Purkinje cells; release GABA
    • Inhibit the cerebellar nuclei and vestibular nuclei.
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11
Q

Action of basket cells and stellate cells?

A

Synapse on purkinje cells -> release GABA-> inhibit them.

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12
Q

What are the two afferent neurons that project to the cerebellum?

A

1. Climbing fibers

2. Mossy fibers

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13
Q

Climbing fibers are afferent fibers that project to ___________ cells.

Mossy fibers are afferent fibers that project to ___________ cell.

A
  • Climbing fibers are afferent fibers that project to purkinje cells.
  • Mossy fibers are afferent fibers that project to granule cells.
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14
Q

Are climbing fibers and mossy fibers excitatory or inhibitory?

A

Excitatory.

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15
Q

Describe climbing fibers (one type of cerebellar afferent fiber)

A

Climbing fibers

  • Myelinated
  • Excitatory
  • Project from the inferior olive and synapse on purkinje cells
  • Convey information regarding movement errors -> cerebellum.
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16
Q

Describe mossy fibers (one type of cerebellar afferent fiber)

A
  • Excitatory
  • [Spinal cord, reticular formation, vestibular system and pontine nuclei] -> [granule cells]
  • Convey information about: somatosensory, arousal, equilibrium and cerebral cortex motor info to cerebellum
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17
Q

Besides afferent fibers synapsing on their respesctive synapses, they also do what?

A

Send collaterals to deep cerebellar nuclei.

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18
Q

There are 3 functional lobes of the cerebellum. What are they?

A

1. Vestibulocerebellum

2.Spinocerebellum

2. Cerebrocerebellum

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19
Q

Cerebrocerebellum is formed by the _____________ and it is involved in in _____________________.

A

Cerebrocerebellum is formed by the lateral hemispheres. It is involved in precise, coordinated movements of the extrememities.

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20
Q

Cerebrocerebellum

Input:

Output:

A
  • Input: cerebral CTX (premotor, sensorimotor) via pontine nuclei.
  • Output: go to the VPL of the thalamus and red nucleus
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21
Q

Spinocerebellum is made up of the of the ______________

A

made up of the of the vermis and paravermal region of the cerebellar hemispheres.

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22
Q

Spinocerebellum is involved with

A

axial and LE movements; gait and station by integrating sensory input with motor commands to make adaptive motor coordination.

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23
Q

In the spinocerebellum, the

  • Vermis: contains ___________
  • Paravermal regions: contain ___________
A
  • Vermis: contains axial UMN (for postural muscles)
  • Paravermal regions: contain lateral UMN (limb muscles)
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24
Q

Input and output to spinocerebellum

A
  • Input: spinocerebellar tract
  • Output: [red nucleus, VPL of the thalamus and reticular formation] go to the
    • rubrospinal
    • vestibulospinal
    • reticulospinal tracts
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25
Q

Vestibulocerebellum the functional equivalent to the _____________.

A

the functional equivalent to the flocculonodular lobe (nodulus and flocculus).

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26
Q

Vestibulocerebellum is involved in _________

A

controlling balance** and **ocular reflexes, mainly fixation on a target.

27
Q

Vestibulocerebellum

Input:

Output:

A
  • Input: vestibular system (vestibular nuclei and _CN 8) a_nd visual areas
  • Output: _reticular formation and back to the vestibular nucle_i, which influences eye movement and postural muscles of the head and body, involved in balance and equillbrium
28
Q

Afferent fibers that enter the cerebellum:

Vestibulocerebellum

A

Input: vestibular system (vestibular nuclei and CN 8) via mossy fibers

29
Q

Afferent fibers that enter the cerebellum:

Spinocerebellum:

A

Input: Spinal cord via mossy fibers

  1. anterior spinocerebellar tract
  2. posterior spinocerebellar tract
  3. cuneocerebellar tract
30
Q

Afferent fibers that enter the cerebellum:

Cerebrocerebellum:

A

Input: cerebral CTX

  1. cortico-pontocerebellar via mossy fibers
  2. cortico-olivocerebellar via climbing fibers
  3. cortico-reticulocerebellar via mossy fibers
31
Q

What is important to note about the anterior spinocerebellar tract?

A

The ACS crosses twice: contralaterally at the anterior white commissure and then crosses back in the superior cerebellar peduncle.

32
Q

Information from the SC enters there cerebellum via the _______________.

A

Information from the SC enters via the restiform body of the inferior cerebellar peduncle

33
Q

The inferior cerebellar peduncle is made up of: _______________________

A
  1. restiform body
  2. juxtarestiform body
34
Q

Describe the posterior spinocerebellar tract

A

The posterior spinocerebellar tract carries proprioception from the lower limb.

STAYS IPSILATERAL

  1. 1st order neurons from the sacral or lumbar region, with their cell body in DRG, enter the dorsal horn ascend via gracile fasciculus.
  2. 1st order neurons synapse onto 2nd in the dorsal nucleus of Clark (located from C8-L2)
  3. The 2nd order axons ascend in the posterior spinocerebellar tract -> go through the restiform body of the inferior cerebellar peduncle.
  4. Restiform body of the inferior cerebellar peduncle -> cerebellum.
35
Q

Describe the cuneocerebellar tract

A

The cuneocerebellar tract carries unconscious proprioception from the upper limb.

STAYS IPSILATERAL

  1. 1st order neurons, with their cell body in DRG, enter the dorsal horn and ascend via cuneate fasciculus.
  2. 1st order neurons synapse with 2nd order neurons in the accessory (external or lateral) cuneate nucleus in the lower medulla
  3. 2nd order axons then enter into the restiform body of the inferior cerebellar peduncle.
  4. Restiform body of the inferior cerebellar peduncle-> cerebellum
36
Q
  • Anterior Spinocerebellar Tract*
  • Takes information from the __________. It is not super important except for 3 facts:*
A
  • Takes information from the lower limb. Not super important except for the following three facts:
    • Helps in motor correction
    • Decussates twice to terminate ipsilaterally in the cerebellum (AWC and superior cerebellar peduncles)
    • Enters via the superior cerebellar peduncles
37
Q

· Axons from the vestibular nuclei and CN XIII enter via…

A

Axons from the vestibular nuclei and CN XIII enter via the juxtarestiform body of the inferior cerebellar peduncle unlike the axons from the spinocerebellar tracts.

38
Q

Cerebrocerebellar System: afferents. how do they enter?

A
  • The olivary climbing fibers ascend to the cerebellum via the restiform body of the inferior cerebellar peduncle.
  • All other information from the cerebral cortex synapses in the pontine nuclei, which enter via the middle cerebellar peduncle.
39
Q

4. Describe the organization of fibers entering or leaving the cerebellar peduncles.

Describe the inferior cerebellar peduncle.

A
  • Inferior cerebellar peduncle is made up of the [restiform body and juxtarestiform body].
    • Primary afferent pathway from the SC.
    • Primary efferent pathway for the anterior spinocerebellar tract
    • Major efferent for the vestibulocerebellum
40
Q
  1. Describe the organization of fibers entering or leaving the cerebellar peduncles.

Describe the middle cerebellar peduncle.

A

Largest and contains afferents from the pontine nuclei (which receive afferents from the cerebral CTX) -> cerebrocerebellum system.

41
Q
  1. Describe the organization of fibers entering or leaving the cerebellar peduncles.

Describe the superior cerebellar peduncle.

A
  • Primary EFFERENT route from [globose, emboliform and dentate nuclei] of the cerebellum.
  • Anterior spinocerebellar tract enters via superior cerebellar peducles.
42
Q

What are the functions of each functional region of the cerebellum?

A
  1. Vestibulocerebellum: eye movement and neck and trunk movements
  2. Spinocerebellum: Axial and LE movements and Gait and station
  3. Cerebrocerebellum: Precise, coordinated movements of extremities (mainly upper extremity)
43
Q

6. Describe the flow of information into and out of the cerebellum (afferents, deep nuclei, efferents.)

Efferents signals are carried by the _________ _________, except ….

A
  • Efferent signals are carried by purkinje fiber -> deep cerebellar nuclei, except for information from the [vestibulocerebellum -> vestibular nucleus], which bypass the deep nuclei via the [inferior cerebellar peduncles].
44
Q

The cerebrocerebellum sends purkinje efferents to:

A

o The cerebrocerebellum sends purkinje efferents to:

  1. Dentate nucleus
  2. (interposed nuclei) globose and Emboliform nuclei
  • > red nucleus and VPL of the thamalus
  • > pre-motor cortex (motor planning)
45
Q

The spinocerebellum sends purkinje efferents to:

A

o The spinocerebellum sends purkinje efferents to:

  1. Dentate nucleus -> red nucleus and VPL of the thalamus
  2. Globose and Emboliform nucleus -> red nucleus and VPL of the thalamus
    1. Primary – mostly through the paravermal region.
  3. Fastigial nucleus -> retricular formation
    1. Mostly through the vermis.

-> Motor cortex and brainstem to help with motor execution

46
Q

The vestibulocerebellus sends purkinje efferents to:

A
  • Fastigial nucleus ->LMN in the pontine and medullar RF to influence reticulospinal tracts.
  • Return directly to the vestibular nucleus, bypassing the deep cerebellar nuclei.
    • inhibit MN of the vestibulospinal tract
47
Q

Unilateral cerebellar lesions will always show ______ deficits. Why?

A

Unilateral cerebellar lesions will always show ipsilateral deficits.

  • Because fibers cross and enter contralateral red nucleus of the cortex and then descending fibers cross back and innervate the muscles.
48
Q

What is a common symptom to lesions of the cerebellum?

A

Ataxia

49
Q

What is ataxia?

A

Voluntary, normal strength, jerky inaccurate movements not associated with hyperstiffness.

50
Q

Vestibulocerebellum connects the_____________ and the __________. Lesions will cause:

A

connects the vestibular system and the flocculonodular lobe.

ASK YOURSELF: what is the function? Eye movements and neck and trunk movements.

Lesions will cause:

  • Eye movement and postural muscle deficits
    • · Nystagmus

· Truncal ataxia: hard staying sitting and standing balance

· Truncal instability (tibubation), preventing patients from tandem walking.

51
Q

Spinocerebellum connects the ________ ->__________.

Lesions will cause problems with

A

Spinocerebellum connects the cutaneous and proprioceptive information from the SC -> vermis and paravermis regions

Axn: Axial and LE movements and Gait and station

  1. Gait and station
    1. Gait and truncal ataxia: wide-based and staggering base
    2. Cant tandem walk
    3. NO nystagmus
52
Q

Lesions of the Cerebrocerebellum will cause

A

AXN: precise and coordinated movements of the extremeties (mainly UE)

· 1. Dysarthria (scanning speech)

· 2. Ataxic gait – staggering gait with a tendency to fall toward side of lesion

· 3. Decomposition of movements

·Limb ataxia manifestations

    1. Dysdiadochokinesia – inability to perform rapidly alternating, repetitive movements
    1. Dysmetria- cannot accurately move an intended distance
  • 6. Action tremor- limb shakes during voluntary movement. As you get closer to the target, the tremor gets bad.
53
Q

What is Dysarthria

A

scanning speech

54
Q

Dysdiadochokinesia

A

inability to perform rapdily alternaiting reptitive movements

55
Q

Dysmetria

A

cannot accurately move an intended distance

56
Q

Action tremor

A

limb shakes during voluntary movement. As you get closer to the target, the tremor gets worse

57
Q

What is Ataxic gait

A

staggering gait with a tendency to fall to the lesion

58
Q

What is midline ataxia?

A

Ataxis caused by diseases of the vestibulocerebellum and spinocerebellum are called midline ataxias

59
Q
  1. Evaluate the clinical findings of midline ataxia.
A
  1. Truncal instability
    1. Titubation: tremor of the trunk in an anterior-posterior plane at 3-4 Hz
  2. Gait ataxia
    1. Equilibratory (gait) ataxia: wide based, irregular steps with lateral veering
60
Q
  1. Evaluate the clinical findings of appendicular ataxia.
A

Appendicular ataxia: damage to the the cerebellar hemispheres that causes ataxia of the extremities and ataxia of speech (scanning dysarthria).

Patients will have (4):

  1. Hypotonia
  2. Decomposition of movements
  3. Dysmetria
  4. Dysdiachokinesia
61
Q

Differentiate between cerebellar ataxia and sensory ataxia.

A

Cerebellar ataxia: cannot stand with feet together with or without eyes open; normal vibration, propioception and ankle reflexes.

Sensory ataxia: patients can with their feet together WITH their eyes open, but they sway or fall when they are closed; abnormal vibration, propioception and ankle reflexes

62
Q

What tests can we do to test the vesticulocerebellum and spinocerebellum?

A
  1. Station
  2. Walking
  3. Tandem gait
63
Q

What tests can we do to test the cerebrocerebellum?

A
  1. Rapid alternating movements
  2. Finger-to-nose
  3. Toe-to-finger
  4. Heel-to-shin
  5. Rebound and check reflex
  6. Speech

Neuro Exam 3 (18 decks)

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