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Neuroanatomy II > 14 - Cerebellum > Flashcards

14 - Cerebellum Flashcards

1
Q

Cerebellum function

A
  • The cerebellum’s function is to correlate cerebral instructions with information from muscles and provide corrective feedback to the motor cortex.
  • Specifically, it’s role is to calculate velocity, duration, force and timing of muscle action to ensure body movements are carried out with precision.
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2
Q

What else is the cerebellum involved in?

A
  • Related roles of the cerebellum are integrating vestibular information with proprioceptive feedback to maintain balance and upright posture at rest and during locomotion, and integrating eye and head movements.
  • The cerebellum is also involved in “procedural memory”, complex motor learning such as riding a bike, playing a piano.
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3
Q

Three lobes of the cerebellum

A

Anterior lobe
Posterior lobe
Flocculonodular lobe

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4
Q

What separates the anterior and posterior lobes?

A

Primary fissure

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5
Q

What separates the two hemispheres of the cerebellum?

A

Vermis

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6
Q

There are three functional areas of the cerebellum. What are they?

A

1 - Vestibulocerebellum
2 - Spinocerebellum
3 - Cerebrocerebellum

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7
Q

Where is the vestibulocerebellum located?

A

Flocculonudular lobe

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8
Q

What is the function of the vestibulocerebellum?

A

Posture, balance, eye/head movement

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9
Q

What is the input to the vestibulocerebellum?

A

Vestibular system (inner ear and nucleus)

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10
Q

What is the output of the vestibulocerebellum?

A

Vestibular nuclei
Vestibulospinal tracts
Medial longitudinal fasiculus

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11
Q

What is the function of the medial longitudinal fasiculus output of the vestibulocerebellum?

A

It integrates CN III, CN IV and CN VI in order to coordinate eye/head movement

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12
Q

Which deep cerebellar nuclei are associated with the vestibulocerebellum?

A

The vestibular nucleus

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13
Q

Where is the spinocerebellum located?

A

In the vermal/paravermal areas

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14
Q

What is the function of the spinocerebellum?

A

Muscle tone and adjusting movements of axial trunk and proximal limbs

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15
Q

What is the input to the spinocerebellum?

A

Dorsal and ventral spinocerebellar tracts
Cuneocerebellar
Trigeminocerebellar

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16
Q

What is the function of the trigeminocerebellar input to the spinocerebellum?

A

Proprioception

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17
Q

What is the output of the spinocerebellum?

A

Vestibulospinal and reticulospinal tracts

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18
Q

What deep nuclei of the cerebellum are associated with the spinocerebellum?

A

Fastigial and interposed nuclei

The interposed nucleus consists of the globose and emboliform nuclei

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19
Q

Where is the cerebrocerebellum located?

A

In the lateral hemispheres

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20
Q

What is the function of the cerebrocerebellum?

A

Percise control of executed movements

Timing, duration, force, velocity and trajectory of movements, of extremities, especially hands and fingers.

21
Q

What is the input to the cerebrocerebellum?

A 
Corticopontocerebellar tracts (for motor cortex intent)
Olivocerebellar tract
22
Q

What is the output of the cerebrocerebellum?

A

Dentorubrothalamic tract (for feedback to motor cortex via VL nuclei of thalamus)

Rubrospinal tracts

23
Q

Which deep cerebellar nuclei are associated with the cerebrocerebellum?

A

Denate nuclei

24
Q

What fibers do deep nuclei of the cerebellum receive?

A

Purkinje fibers

25
Q

What role do deep nuclei play in the cerebellum?

A

They are the major output of the cerebellum

26
Q

Match the deep nuclei of the cerebellum to their location in the cerebellum and what functional division they are part of

A

Fastigial nucleus

  • vermis
  • spinocerebellar

Interposed nuclei

  • paravermal
  • spinocerebellar

Dentate nucleus

  • hemispheres
  • cerebrocerebellum

Vestibular nuclei

  • flocculonodular lobe
  • vestibulocerebellum
27
Q

All the deep nuclei of the cerebellum have one thing in common… What is it?

A

They all send collaterals back to the cerebellar cortex

28
Q

Are the purkinje cells excitatory or inhibitory on deep cerebellar nuclei?

A

ALWAYS INHIBITORY

29
Q

What is the climbing fiber system?

A

The climbing fiber system consists of the olivocerebellar tract

30
Q

The climbing fiber system synapses on purkinje cells. What type of synapse and what is the ratio?

A
  • Excitatory synapses

- One to one ratio

31
Q

What is the mossy fiber system?

A

The mossy fiber system includes all other inputs to the cerebellar cortex

32
Q

What do the climbing fiber system and the mossy fiber system have in common?

A

They BOTH send excitatory collaterals to deep nuclei

33
Q

How would you summarize the deep cerebellar nuclei output?

A

G. Deep cerebellar nuclei output is a product of excitatory climbing and mossy fibers and inhibitory Purkinje fiber activity.

34
Q

What is the inferior olivary nucleus?

A

It is a nucleus of the cerebellum that extends from the inferior olive to Purkinje cells and is involved in the following processes:

  • Internal clock
  • Procedural learning of motor skills
  • Adaptive learning
  • Corrective action taken by motor cortex

An example of this would be “practice makes perfect” when learning to do a skilled movement such as playing the guitar

35
Q

What are peduncles?

A

Attachments of the cerebellum to the brainstem that serve as pathways

They provide pathways for input ad output to the cerebellum

36
Q

There are three peduncles of the cerebellum - what are they?

A

1 - Superior peduncle
2 - Middle peduncle
3 - Inferior peduncle

37
Q

Superior peduncle

A

Superior peduncle- connects the cerebellum with the midbrain

Major output to the cerebrum

Specifically sends information to the cerebral motor cortex

38
Q

Middle peduncle

A

Middle peduncle- connects the cerebellum with the pons

Major input into the cerebellum

The middle peduncle is INPUT ONLY and the input comes from the cortiopontocerebellar tract

39
Q

Inferior peduncle

A

Inferior peduncle- connects the cerebellum with the medulla

Both input and output are present here

40
Q

Ataxia

A

Ataxia – abnormal gait/stance and abnormal control of voluntary motions, caused by a hemispheric cerebellar lesion

41
Q

Dysmetria

A

Dysmetria – inability to estimate the distance between a moving body part and the target

42
Q

Dysdiadochokinesia

A

Dysdiadochokinesia – inability to carry out rapid, alternating movements regularly

43
Q

Nystagmus

A

Nystagmus – uncoordinated activity of the ocular muscles, resulting in eye deviation towards the side of the lesion

44
Q

Does the motor cortex have unilateral or bilateral connections with the cerebellar hemispheres?

A

Unilateral - The motor cortex has contralateral connections with the cerebellar hemispheres

45
Q

What about the connections between the cerebellum and the spinal cord/brainstem?

A

These connections are UNCROSSED

46
Q

So when there is a lesion in the cerebellum, what will we see?

A

Lesions of the cerebellum typically show ipsilateral (same-sided) signs and symptoms

47
Q

What muscles could be paralyzed from a cerebellum lesion?

A

NONE

Since no cerebellar neurons have direct control of any muscles, there is NO PARALYSIS

48
Q

Case 13

A

A 72-year-old woman developed sudden severe vertigo about 5 hours prior to presentation in the emergency room. The vertigo has persisted and remained severe. She became nauseated and vomited a few times. She has not been able to walk, and cannot even sit on the side of the bed without falling over. There was initially some double vision but this has since resolved. She complains that her left arm is “weak” and heavy. Her speech is mildly slurred. She feels that she is being pulled to the left when she attempts to stand or sit up. Exam shows mild dysarthria (slurred speech), but language function is normal. Bilateral end gaze nystagmus is present, which is much more prominent toward the left. Facial strength and sensation is normal. Despite the patient’s complaint, exam shows strength throughout to be normal. However, there is dysmetria and ataxia involving the left arm, but the right arm is normal. The patient cannot stand or even sit up in bed on her own. Sensation is normal throughout. Head CT in the emergency room was normal.

Neuroanatomy II (10 decks)

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