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SF2- Exam 4 > Cerebellum > Flashcards

Cerebellum Flashcards

1
Q

The cerebellum is packed full of _________ cells.

A

Granular

NOTE:

The cerebellum constitutes only 10% of the brain’s volume, yet it contains over 50% of all neurons

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2
Q

Does the cerebellum come from the alar or basal plate?

A

It develops from the dorsolateral portion of the alar plate

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3
Q

The embryology of the cerebellum suggests it’s a __________ structure

A

sensory

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4
Q

The cerebellum develops from the ___________portions of the alar plate.

A

dorso-lateral

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5
Q

Its major output is to ___________ of the thalamus which projects to areas __________of the cortex

A

Ventrolateral nucleus; 4 & 6

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6
Q

Does sensory information transmitted tot he cerebellum reach cosciusness?

A

NO sensory information, transmitted to the cerebellum reaches consciousness

*the cerebellum receives sensory input from essentially all sensory receptors.

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7
Q

Will alesion to the cerebellum produce sensory problems?

A

No. Lesion will produce motor problems but not sensory problems

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8
Q

Feed forward

A

Everything has been programmed and there is no way to adjust once the object of concern reaches the point of no return

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9
Q

What must be “known” in feedforward actions?

A
  1. starting position
  2. (anticipated) target position
  3. properly timed sequence of muscle contractions of appropriate velocities/strengths
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10
Q

It is currently thought that the cerebellum acts a comparator that compensates for errors in movements by comparing ___________ with performance

A

intentions

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11
Q

What is corollary discharge?

A

Internal feedback or efferent copy for the intended movement

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12
Q

What is reafference?

A

External (sensory) feedback for the actual movement response

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13
Q

When you look at the input the cerebellum receives, in terms of intentions, if the cortex says “I want to execute this movement” the cerebellum gets a copy of it; this is called _____________.

A

corollary discharge

*A signal is going down to the spinal cord to the area of the upper limb, cervical spinal cord, and that is what the motor cortex is telling it to do.

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14
Q

The sensory info the cerebellum receives does not reach consciousness. What is it used for?

A

The sensory information that the cerebellum receives is used for the automatic regulation and control of motor function (including posture).

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15
Q

Through comparisons of external & internal feedback signals, the cerebellum is able to:

A
  1. Correct ongoing movements when they deviate from the intended course (efferent copy)
  2. Modify motor programs in the CNS so that future movements attain their goals, ie. motor learning
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16
Q

External feedback to the cerebellum come from:

A
  1. Vestibular nuclei
  2. Spinal cord
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17
Q

The cerebellum receives a massive amount of input from the vestibular system; it receives direct afferents, first order neurons, from bipolar neurons of vestibular system and some of these neurons go directly to the _____________ of the cerebellum

A

flocculonodular lobe

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18
Q

From the spinal cord, the cerebellum receives information from the ___________and around the joint.

A

golgi tendon

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19
Q

The dorsal and ventral spinocerebellar tracts send information from the ________ half of the body

A

lower

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20
Q

The cuneocerebellar and rostrocerebellar give positional information about the positions of the ___________ limb

A

upper

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21
Q

What information does the trigeminocerebellar tract provide to the cerebellum?

A

Informationa bout the postion of the head

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22
Q

Main source of internal feedback is from the _________.

A

cortex​

NOTE: The info from the cortex first passes through the pons and is then sent to the cerebellum via pontocerebellar fibers which are contralateral

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23
Q

What type of projections are the vestibulocerebellar fibers?

A

Bilateral

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24
Q

The output of the cerebellum goes to __________ systems of the brain

A

motor

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25
Q

The cerebellum forms a roof over the _________.

A

4th ventricle

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26
Q

Which part of the cerebellum communicates with the vestibular nuclei?

A

flocculonodular node

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27
Q

When are the cerebellar tonsils clinically important?

A

When there is an increase in intracranial pressure

NOTE: If this happens they can herniate through the foramen magnum, compress the medulla, and cause death

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28
Q

Herniation of the cerebellar tonsils causes compression of the ___________

A

Medulla

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29
Q

The cerebellar tonsils- they can herniate through the foramen, compress the medulla and compress the cardiovascular and respiratory centers in the medulla and cause cessation of breathing and death. This is an _________malformation.

A

Arnold Chiari Type II

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30
Q

As an epidural hematoma gets larger, the uncus of the temporal lobe will herniate through the tentorium cerebelli and compress the _________

A

Oculomotor nerve

*patient has fixed and dilated pupils

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31
Q

The ______________separates flucculonodular & posterior lobes.

A

posterolateral fissure

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32
Q

Label

A
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33
Q

The cerebellum is divided into 3 subdivisions. What are they and what is the function of each?

A

Vestibulocerebellum

  • regulates balance and eye movements

Spinocerebellum

  • receives somatosensory input from the spinal cord
  • it uses this information to modify descending motor commands to facilitate movement, maintain balance, and control posture.

Cerebrocerebellum

  • communicates with the cerebral cortex and is thought to be involved with planning and initiating movement.
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34
Q

The vestibular cerebellum corresponds directly to which part of the cerebellum?

A

flocculonodular lobe

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35
Q

What are the two parts of the spinocerebellum?

A
  • The vermis
  • The paravermal lobe (intermediate)
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36
Q

What are the components of the cerebrocerebellum?

A

The 2 lateral hemispheres

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37
Q

The flocculonodular lobe receives a lot of input from ____________.

A

Vestibular nuclei bilaterally and the vestibular nerve

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38
Q

The vermis receives input from ___________.

A
  • Receives input from the trigeminal system and body trunk, afferents; golgi tendon organs and muscle spindles
  • Receives input from visual and auditory systems because they are centrally located sensory receptors
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39
Q

The intermediate lobe receives input from receptors found in the _________.

A

limbs

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40
Q

Medial descending system- axons are going to rexed lamina_________

A

9

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41
Q

What two tracts are apart of the lateral descending system?

A

Lateral corticospinal tract

Rubrospinal tract

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42
Q

What tracts are apart of the medial descending system?

A
  1. anterior corticospinal
  2. vestibulospinal
  3. reticulospinal
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43
Q

How is the cerebellum connected to the rest of the brain?

A

It gets afferents and efferents through peduncles

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44
Q

Peduncles connect the cerebellum to the ___________.

A

brainstem

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45
Q

_____________connects to cerebellum to the midbrain

A

superior cerebellar peduncle

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46
Q

______________ connects cerebellum to the pons.

A

middle cerebellar peduncle

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47
Q

________________ connects the cerebellum to the medulla.

A

inferior cerebellar peduncle

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48
Q

Primarily, the cerebellum sends it’s efferents through _____________.

A

Superior cerebellar peducle

NOTE: The superior cerebellar peducle receives a small amount of afferents

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49
Q

Of the cerebellar peduncles, which only recieves afferents?

A

MIDDLE CEREBELLAR PEDUNCLE

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50
Q

In general, the cerebellum receives it afferents from which structures?

A

In general, the cerebellum receives its afferents through the:

  • inferior cerebellar peduncle (spinal cord & medulla)
    • Has a tiny bit of efferents
  • middle cerebellar peduncle (pons - cortical input)
    • ONLY afferents

*The superior cerebellar peduncle also has a bit of peducles

51
Q

The inferior peducle receives afferents from which fibers?

A
  1. Vestibulocerebellar
  2. Spinocerebellar
  3. Inferior olivocerebellar
52
Q

There is output through the inferior peduncle and they form the ___________ and ___________tracts.

A

cerebellovestibular; cerebelloreticular

53
Q

The middle cerebellar peduncle receives afferents from which fibers?

A

Pontocerebellar

*Cortical input goes to basilar pons, synapses with pontine neurons and these neurons cross and send projections to the contralateral side

54
Q

There is input through the superior peduncle and it forms the ________________, coming from the lower part of the spinal cord from the lower limbs

A

ventrospinocerebellar tract

REMEMBER: The superior cerebellar peduncle is the MAJOR output from the cerebellum

55
Q

What are the efferents coming from the superior cerebellar peduncle?

A

•Cerebellothalamic goes to VL of the thalamus

•Cerebellorubal is another target (aka the red nucleus)

56
Q

The gray matter of the cerebellum forms a_____________ and ____________.

A

cortex; deep cerebellar nuclei

57
Q

The cortex of the cerebellum is organized into 3 distinct layers. What are they?

A
  1. molecular layer
    * largest and thickest
  2. Purkinje cell layer
    * single layer of large cells
  3. granular layer
    * packed full of probably half the neurons in the brain
58
Q

Which component of the cerebellum is the input component? Which is the output component?

A

Cortex- Input

Deep cerebellar nuclei- Output

59
Q

What are the deep cerebellar nuclei?

A
  • Dentate nuclei
  • Interposed nuclei (emboliform and globose)
  • Fastigal
60
Q

Label the layers of the cerebellum cortex

A
61
Q

There are 5 cells with the in the cerebellar cortex. List them and state whether they are excitatory or inhibitory.

A
  1. granular cells* excitatory
  2. Purkinje cells* inhibitory
  3. stellate cells inhibitory
  4. basket cells inhibitory
  5. Golgi cells inhibitory
62
Q

Which cell type (of the cerebellar cortex) is being described below?

  • very small cell bodies, probably the smallest in the nervous system
  • They have long axons that go to the molecular layer and then it splits and runs parallel to the folia, forming parallel fibers of the cerebellum.
  • Small but excitatory
A

Granular cells

63
Q

Which cell type (of the cerebellar cortex) is being described below?

  • cells- largest in the nervous system
  • Large cell bodies and dendritic arborization which can synapse with millions of axons
A

Purkinje Fibers

NOTE: Even though you have zillions of granular cells the output of the entire cortex is coming from Purkinje cells

64
Q

The axon of ___________ cells is the sole output of the cerebellar cortex.

A

Purkinje

*Projects to the deep cerebellar nuclei (& vestibular nuclei)

65
Q

Dendrites of Pukinje neurons fan out ___________ to the folia; however, they appear as narrow sprouts in sections parallel to the folia.

A

perpendicular

66
Q

Purkinje cells project to the _____________ and are the sole (inhibitory) output of the cortex.

A

deep cerebellar nuclei

EXCEPTION: Purkinje cells of the flucculonodular lobe project to the 4 vestibular nuclei which can be thought of as deep cerebellar nuclei

67
Q

The deep cerebellar nuclei goes to the __________, _________,___________, and _________.

A

thalamus, red nucleus, brainstem, and reticular formations

68
Q

Three different categories of afferent fibers conduct nerve impulses to the cerebellum:

A
  1. Aminergic fibers (modulatory)
  2. Mossy fibers (exicitatory)
  3. Climbing fibers (excitatory)
69
Q

What are the two sources of aminergic fibers that modulate activitity cerebellum neurons?

A
  1. Dorsal raphe nuclei: seratonin
  2. locus ceoruleus: norepinephrine
70
Q

The locus coeruleus of the midbrain sends ___________fibers to cerebellum and most of the CNS.

A

noradrenergic

*It is thought to modulate the activity of the cerebellum and most the CNS

71
Q

Climbing Fibers originate from the ____________.

A

inferior olivary nucleus (complex)

*These axons pass through the pons and enter the cerebellum via the inferior cerebellar peduncle where they form synapses with the deep cerebellar nuclei and Purkinje cells.

72
Q

Climbing fibers wrap around the soma and climb the dendrites of ___________ cells making numerous excitatory contacts

A

Purkinje

*Early in development, Purkinje cells are innervated by multiple climbing fibers, but as the cerebellum matures, these inputs gradually become eliminated resulting in a single climbing fiber input per Purkinje cell.

73
Q

Climbing fibers run ___________ to the folia

A

perpendicular

74
Q

What type of response does the action potential evoked by climbing fibers produce?

A

A single action potential in a climbing fiber evokes a complex spike in the Purkinje cell

*Climbing fibers provide excitatory and low frequency input (1 spike/s)

75
Q

Along with the complex spike induced by the action potential of climbing fibers, what else is induced? What’s the clinical significance of this?

A

A large Ca2+ influx

*•It is believed that Ca is very important and involved for neuronal plasticity. So motor learning is thought to be related to these climbing fibers.

76
Q

Mossy fibers originate from all cerebellum afferent. What is the exception?

A

the inferior olivary nucleus

*Climbing fibers orginate from here

77
Q

Aside from purkinje neurons, climbing fibers also send fibers to ____________.

A

Deep cerebellar nuclei

78
Q

Each mossy fibers stimulates Purkinje neurons indirectly via ________ cells.

A

Granule cells

79
Q

Differentiate climbing and mossy fibers.

A

Climbing

  • Synapose directly on Purkinje neurons
  • Low frequency
  • Complex spike activity
  • Originate from inferior olivary complex

​Mossy

  • Synapse indirectly Purkinje neurons (via granule cells)
  • Orginate from all cerebellar afferents(execept one)
  • Hight frequency, must be summated
80
Q

Cerebellar ____________cells project up through the Purkinje layer into the molecular layer where they branch out into parallel fibers that spread through Purkinje cell dendritic arbors. These parallel fibers form thousands of excitatory granule-cell–Purkinje-cell synapses onto the intermediate and distal dendrites of Purkinje cells using glutamate as a neurotransmitter.

A

granule

*Granule cells have very little power overy a single Purkinje cels but have alot of power over many Purkinje cells.

81
Q

You have a mossy fiber that synapses with a granule cell and it gives off fibers to the ___________.

A

deep cerebellar nuclei

82
Q

The spike below is evoked by which fiber type?

A

Climbing fibers

83
Q

Which fiber type is the spike in the picture evoked by?

A
84
Q

Label

A
85
Q

All output from the cerebellar cortex comes from purkinje cells. Where is this output going?

A

To the deep cerebellar nuclei (Fastigal, Dentate, and interposed)

86
Q

Label

A
87
Q

The fibers from the vermis go to which deep cerebellar nuclei?

A

Fastigal

88
Q

Fibers from the intermediate or paravermal region go to which deep nuclei?

A

Interposed nuclei

89
Q

The cerebrocerebellum is going to connect to the ____________ (deep cerebellar nuclei)

A

Dentate

90
Q

Of the major sections of the cerebellum, which section does not project to deep cerebellar nuclei?

A

Vestibulocerebellum

91
Q

The _______ and ________ nuclei are involved in motor execution, via the medial and lateral descending pathways.

A

Fastigial and Interposed

92
Q

The _______ nucleus is involved in motor planning via areas 4 and 6.

A

dentate

93
Q

The cerebellum receives its MAJOR input from the cortex which is relayed through the ________.

A

pons

94
Q

The corticopontine tract originates from which 4 areas?

A
  1. premotor cortex (area 6)
  2. motor cortex (area 4)
  3. somatosensory cortex (areas 3, 1, 2)
  4. higher order somatosensory cortex (area 5)
95
Q

The corticospinal tract (pyramids) is about ____million fibers. The corticopontine tract is about________ million.

A

1; 19

96
Q

Corticopontine fibers pass through the ___________on either side of the corticospinal tract

A

cerebral peduncle

97
Q

Label

A
98
Q

Corticopontine fibers terminate in nuclei found in the __________ pons.

A

basile

99
Q

Pontocerebellar fibers cross in the pons & reach the cerebellum via the ____________.

A

middle cerebellar peduncle

100
Q

label

A

Caudal pons

101
Q

Efferents from pontine nuclei form ___________ fibers terminating primarily in the contralateral cerebrocerebellum.

A

mossy

102
Q

What is the pathway for denate nucleus?

A
  1. The axons will cross to the opposite side and they will terminate in thalamus, specifically the VL.
    * The place that these axons decussate will form the superior cerebellar peduncle. So terminating mostly in VL, some will also go to the VA and then some to the VLP
  2. From the thalamus, the thalamocortical neurons are going to be going to the motor cortex, most importantly area 4, 6.

*Some axons from the dentate nucleus also project to the red nucleus.

103
Q

A small portion of dentate efferents synapse in the __________ before being relayed to thalamus & cortex

A

red nucleus (parvocellular part)

104
Q

Cerebellar signs are usually _________because the decussations of the corticopontine-cerebellar tract and the cerebellothalamic tract .

A

Ipsilateral

105
Q

Decussation of the superior cerebellar peducle is a landmark of which part of the brainstem?

A

Mid brain

106
Q

What is the pathway of the interpose nucleus?

A
  1. Axons will cross at the decussation of the superior cerebellar peduncle
  2. They will terminate mostly in VL and the axons of the thalamocortical neurons will terminate at motor areas of the cortex mostly areas 4 and 6.

REMEMBER: The interpose nucleus is involved is execution of limb movements (along with the fastigial nucleus)

107
Q

Efferents from the interpose nucleus go to areas 4 and 6. Where else do they go?

A

Red nucleus (magnocellular part)

*The decussate at the superior cerebellar peduncle and then synapse on the magnocellular part of the red nucleus, the older part of the nucleus. The axons from here cross the midline again and form the rubrospinal tract

108
Q

Lesion of the cerebellar cortex delays the ____________.

A

initiation of movement

109
Q

The fastigial nucleus gets to its targets via the ___________

A

Inferior cerebellar peduncle

110
Q

What are the two main targets of the fastigial nucleus?

A

a. vestibular nuclei (vestibulospinal pathways)
b. reticular formation (reticulospinal pathways)

111
Q

What are the effects of the inputs from the fastigial nucleus?

A
  • Posture
  • Automatic movements
112
Q

What are possible symptoms of lesion to the cerebellum?

A

Dyssynergia

Dysmetria

Dysdiadochokinesia

Dysarthria

Ataxia

Wide Gait

Intentional tremor

Nystagmus

113
Q
A
114
Q

Explain intential tremor.

A

•If the patient is just standing, everything is fine. Ask them to touch their nose, as they get closer and closer to their nose you will start to see more and more tremors. This is because the error signal, the closer and closer you get to the target the greater the error signal so you start getting this tremor.

115
Q

What conditions can cause the anterior lobe of the cerebellum to degenerate?

A

Alcoholism

Thiamine deficiency

116
Q
A
117
Q

What are the type of clinical signs that indicate a person has cerebellar lesion?

A
  • The major changes is that it takes longer for that individual to execute the movement. That is very demonstratable.

REMEMBER: The cerebellum is responsible for initiating movement

118
Q

If you had a _________ lesion, each joint would move independently and It would be a very jerky movement.

A

cerebellar

NOTE: Cerebellar lesions are ipsilateral

119
Q

How can patients with vermal damage be distinguished from patients with damage to the dorsal columns?

A

With the Romberg sign

  • Vermal lesion: patients loose balance with their eyes open falling towards the lesion.
  • Dorsal column lesion – patients loose balance with their eyes closed.
120
Q
A
121
Q

What disorder is being described below?

An inherited autosomal recessive disease resulting in low levels of frataxin required for mitochondrial electron transport

A

Fredrick’s Ataxia

122
Q

What are the symptoms of Fredrick’s ataxia?

A

A.Muscle weakness in extremities

B.Ataxia and loss of coordination and dysmetria

C.Dysarthria & Dysphagia

123
Q

In Fredrick’s ataxia, the CNS and PNS are both affected. Which parts of CNS are affected? What about the PNS?

A

PNS: Large myelinated axons & dorsal root ganglion

CNS: spinal cord

1) dorsal root ganglion
2) Clarke’s nucleus and dorsal spinocerebellar tracts
3) dorsal columns
4) corticospinal tracts (Betz cells)

NOTE: From Clarkes nucleus and the spinocerebellum tracts, the dorsal columns are affected.

SF2- Exam 4 (21 decks)

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