Unit 2: Vestibular System Flashcards

1
Q

The vestibular system is responsible for helping to monitor the

A

Orientation of the head in 3-dimensional space

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2
Q

Vestibular data is collected and integrated into the CNS with visual and proprioceptive data used to:

A
  1. Maintain general body equilibrium

2. Coordinate eye movements with movements of the head

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3
Q

Structures within the vestibular system include

A
  1. Apparatus within the inner ear
  2. Vestibular division of CNVIII
  3. CNS pathways
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4
Q

The saccule and utricle are dilations of the membranous labyrinth and filled with

A

Endolymph

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5
Q

The vestibule and semicircular canals are within the

A

Osseous labyrinth

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6
Q

The utricle, saccule and semicircular ducts are within the

A

Membranous labyrinth

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7
Q

Along the wall of each saccule and utricle there is a “patch” of sensory epithelium (the vestibular receptors) called:

A

Maculae

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8
Q

Specialized mechanoreceptors that monitor the position of the head (static and kinetic)

A

Maculae

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9
Q

The stereocilia (hair cells, aka sensory cells) project from the apical edge with one long single “hair” called

A

Kinocilium

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10
Q

If hair cells/stereocilia bend toward the kinocilia, what happens to firing rate?

A

Increases firing rate

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11
Q

If hair cells/stereocilia bend away from the kinocilia, what happens to firing rate?

A

Decrease firing rate

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12
Q

The gelatinous membrane that contains otoliths is called

A

Otolithic membrane

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13
Q

Crystals comprised of protein and calcium carbonate:

A

Otoliths

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14
Q

What innervates the base of each hair cell?

A

Dentrites of 1˚ vestibular neurons

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15
Q

Maculae best monitor:

A

Tilting head movements and acceleration and deceleration phases of linear movement

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16
Q

How many semicircular ducts per inner ear?

A

3

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17
Q

The posterior semicircular duct is in the ____ plane and monitors information in the _____ plane

A

Vertical; vertical

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18
Q

The anterior (superior) semicircular duct is in the ____ plane and monitors motion in the ___ plane

A

Vertical; vertical

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19
Q

The lateral (horizontal) semicircular duct slopes posteriorly and inferiority 30˚ to the ______ plane and monitors motion in the _______ plane

A

Horizontal; horizontal

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20
Q

Semicircular ducts filled with:

A

Endolymph

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21
Q

Semicircular ducts surrounded by

A

Perilymph

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22
Q

Each of the 3 semicircular ducts has a dilation/bulbous end called

A

Ampulla

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23
Q

Along the wall of each ampulla in the semicircular ducts, there is a patch of specialized sensory epithelium called

A
Crista ampullaris 
(plural =cristae)
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24
Q

Cristae ampullaris are what kind of receptors?

A

Mechanoreceptors

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25
Q

Cristae ampullaris monitor what kind of movement?

A

Rotational/angular head movement

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26
Q

The gelatinous membrane in which hairs of the crista ampullaris are called embedded in

A

Cupula

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27
Q

1˚ vestibular neuron cell bodies are located in

A

Vestibular/Scarpa’s ganglion

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28
Q

Cristae ampullaris change their excitability (static discharge) when head undergoes what kind of motion?

A

Angular/rotational

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29
Q

Head rotates/moves to the RIGHT, the RIGHT duct rotates to the ____, and the endolymph moves to the ____.

A

Right; left

Endolymph lags

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30
Q

Ampullopetal

A

Movements facilitates cristae ampullaris (aka endolymph moves toward cristae)

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31
Q

Ampullofugal

A

Movement inhibits cristae ampullaris (aka endolymph moves away from cristae)

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32
Q

Decreases discharge movement of cristae / inhibition of the crista ampullaris

A

Ampullofugal

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33
Q

Increase discharge movement of cristae / facilitation of crista ampullaris

A

Ampullopetal

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34
Q

Rotation of head to the right (acceleration phase). What is the endolymph doing in the right vs left lateral ducts?

A

Right lateral duct endolymph is moving through ampulla and into utricle = ampullopetal flow

Endolymph in left lateral duct flows through ampulla into duct = ampullofugal flow

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35
Q

Peripheral processes of the primary vestibular neurons innervate hair cells of the:

A

Cristae ampullaris and maculae

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36
Q

Central processes of vestibular neurons enter the brainstem as part of the CN

A

VIII

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37
Q

Some central axons of vestibular pathway enter the ______ through ICP

A

Cerebellum

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38
Q

Most central axons of the vestibular pathway will synapse in the

A

Vestibular nuclear complex

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39
Q

The vestibulospinal tract is ipsilateral or contralateral tract?

A

Ipsilateral

40
Q

The descending medial longitudinal fasciculus pathway is a ipsilateral/bilateral pathway

A

Bilateral - includes axons from the ipsilateral and contralateral vestibular nuclear complex

41
Q

The vestibular nuclear complex is located in:

A

The floor of the IV ventricle in the pons and medulla AKA the rhomboid fossa

42
Q

What are the 2 tracts/pathways that project from the vestibular nuclear complex into the spinal cord?

A

Vestibulospinal Tract and Medial Longitudinal Fasciculus (MLF)

43
Q

Descending Medial Longitudinal Fasciculus (MLF) help

A

Regulate tone of neck muscles in order to maintain balance of head as it moves through space

44
Q

Ascending Medial Longitudinal Fasciculus (MLF) fibers influence activity of cranial nerve(s):

A

VI, IV, III

45
Q

Ascending Medial Longitudinal Fasciculus (MLF) help

A

Both eyes move together in parallel or ‘conjugate’ fashion

46
Q

Vestibular data also projects to the cerebellum via VIII nerve directly to the

A

Vestibulocerebellum AKA archicerebellum

47
Q

Vestibular data that projects to the cerebellum project through what structure?

A

Inferior cerebellar peduncle (AKA restiform body)

48
Q

Cell bodies of primary sensory vestibular neurons/bipolar neurons comprise this ganglion:

A

Vestibular ganglion aka Scarpa’s ganglion

49
Q

Peripheral processes of vestibular neurons innervate:

A

Hair cells of cristae ampullaris and maculae

49
Q

The tips of “hair” cells in the vestibular system are embedded in what?

A

Otolithic membrane or cupula

49
Q

Primary vestibular neuron cell bodies are located where?

A

Vestibular ganglion (aka Scarpa’s ganglion)

50
Q

What innervates the base of each hair cell?

A

Dendrites of primary vestibular neurons whose cell bodies are located in the vestibular ganglion

51
Q

Is the vestibulospinal tract continuous or discontinuous through the spinal cord

A

Continuous - it extends the entire length of the cord

52
Q

Projections from the vestibular nuclear complex synapse on interneurons or motor neurons that innervate what?

A

postural muscles - such that when the head is moved, body equilibrium is maintained

53
Q

Primary vestibular neuron axons that project into the medial longitudinal fasciculus (MLF) synapse in cervical cord segments on interneurons or motor neurons that innervate what?

A

neck muscles - helps to regulate tone of neck muscles in order to
maintain the balance of the head as it moves through space

54
Q

The vestibulocerebellum (archicerebellum) utilizes the information that is receives to do what?

A

influence the activity of muscles used in posture and balance

55
Q

What areas of the cerebrum receive vestibular data?

A

Parietal and temporal lobes and insula

56
Q

The vestibular pathways to the cerebrum contribute to what conscious awareness?

A

Conscious awareness of the precise position of the head in space

57
Q

When an individual, walking in a straight line, turns to the right, what happens to endolymph flow in the right lateral duct and how does it affect the discharge of the unilateral crista?

A

It is ampullopetal which will cause the discharge of the unilateral crista to increase.

58
Q

When an individual, walking in a straight line, turns to the right, what happens to endolymph flow in the left lateral duct and how does it affect the discharge of the unilateral crista?

A

It is ampullofugal which will cause the discharge of the unilateral crista to decrease.

59
Q

vestibular data from the inner ears projects to the _______ and modifies the activity of central vestibular pathways which are ________ and _______.

A
  • vestibular nuclear complex

- Vestibulospinal tract, Medial longitudinal fasciculus tract

60
Q

As the head rotates to the right, vestibular data drives a ________ that enables the eyes to maintain visual fixation on stationary objects as the head is moving.

A

vestibulo-ocular or vestibulokinetic reflex

61
Q

As part of the vestibulo-ocular or vestibulokinetic reflex, as the head rotates to the right, the eyes will initially move slowly to the ________. This is called _______ phase of the reflex?

A
  • left

- slow drift

62
Q

A slow drift reflex of the eyes to the left, requires facilitation of the right CN ______ that innervates the right ______ muscle and facilitation of the left CN ______ that innervated the left ______ muscle.

A
  • 3, medial rectus

- 6, lateral rectus

63
Q

The slow drift phase of the reflex is dependent on the _________ and is mediated by __________.

A
  • vestibular data from the inner ear

- the ascending MLF

64
Q

After the slow drift phase of the reflex, the eyes quickly move to the ________ in the fast drift phase of the reflex.

A

Opposite direction

65
Q

A fast drift reflex of the eyes to the right, requires facilitation of the right CN ______ that innervates the right ______ muscle and facilitation of the left CN ______ that innervated the left ______ muscle.

A
  • 6, lateral rectus

- 3, medial rectus

66
Q

Is the fast drift phase of the reflex driven by vestibular data?

A

No, it is considered a corrective maneuver

67
Q

The pattern of slow and fast drift movements of the eyes are collectively known as what?

A

Nystagmus

68
Q

The direction of nystagmus is designated as the direction of which component of the reflex?

A

The fast component

  • thus with rotation of the head to the right, nystagmus is to the right
69
Q

What are two test used for testing the integrity of the vestibular system?

A
  • rotation test

- caloric test

70
Q

What are the steps of the rotation test?

A
  • patient seated in swivel chair with head tilted 30 degrees forward to get the lateral semicircular ducts in the horizontal plane
  • patient is rotated at a constant velocity for about 10-15 turns so that endolymph is moving at the same speed as the head and lateral semicircular ducts and crista ampullaris receptors have reached a static discharge rate
  • chair is stopped and patient is asked to stand and point at a distant stationary object
  • observe and evaluate the patient during the post rotation phase
71
Q

During the post rotation phase of the rotation test of the vestibular system, the patient will fall to the ______ (same/opposite) side of rotation in the swivel chair

A

Same

72
Q

During the post rotation phase of the rotation test for vestibular system, the CNS thinks the head/body is rotation to the _______ (same/opposite) side of rotation in the swivel chair.

A

Opposite

73
Q

During the post rotation phase of the rotation test for vestibular system, when attempting to point to a distant object, the patient will past point to the _______ (same/opposite) side of rotation in the swivel chair.

A

Same

74
Q

What are the steps of the caloric test of the vestibular system?

A
  • tilt patient’s head backwards 60 degrees to place lateral ducts in vertical position
  • irrigate the external auditory canal of one ear with either warm or cold water
  • observe and record normal nystagmus response of the caloric test (COWS)
75
Q

The mechanism of the caloric test is that water in the ear will induce convection current in the endolymph. Cold water will cool the endolymph, reduce fluid level and cause _________ movement of the endolymph and ipsilateral crista discharge rate to ________ . The brain interprets this information as rotation of the head to the ________ (opposite/same) side.

A
  • Ampullofugal
  • decrease
  • opposite
76
Q

The mechanism of the caloric test is that water in the ear will induce convection current in the endolymph. Warm water will warm the endolymph, increase fluid level and cause _________ movement of the endolymph and ipsilateral crista discharge rate to ________ . The brain interprets this information as rotation of the head to the ________ (opposite/same) side.

A
  • Ampullopedal
  • Increase
  • same
77
Q

Caloric Test: Cold water. What does the endolymph do?

A

Cools, reduced fluid levels.

78
Q

Caloric Test: Cold water. What is the movement of ipsilateral endolymph in ipsi semicircular duct?

A

Ampullofugal

79
Q

Caloric Test: Cold water. Does the discharge rate increase, decrease or stay the same in the ipsilateral crista?

A

Decrease

80
Q

Caloric Test: Cold water. Brain interprets this information as rotation of the head to what side?

A

Opposite side — left

Ex. Right ear so left rotation interpretation

81
Q

Caloric Test: Cold water. Will cause a slow drift to what side?

A

Ipsilateral — right

Ex. Right ear, right slow drift

82
Q

Caloric Test: Cold water. Will cause a fast drift to what side

A

Contralateral — left

Ex. Right ear, left fast drift

83
Q

Caloric Test: Cold water. Will cause what kind of nystagmus?

A

Contralateral — left

Ex. Right ear, left nystagmus

84
Q

Caloric Test: Cold water. Patient will fall to what side?

A

Ipsilateral side — right

Ex. Right ear, fall to right

85
Q

Caloric Test: Cold water. Patient will past-point to what side?

A

Ipsilateral — right

Ex. Right ear, past-point right

86
Q

Caloric Test: Warm water. What happens to ipsilateral endolymph?

A

Warms, increases fluid level

87
Q

Caloric Test: Warm water. What kind of movement of endolymph in ipsilateral semicircular duct?

A

Ampullopedal

88
Q

Caloric Test: Warm water. discharge rate of ipsilateral crista?

A

Increased

89
Q

Caloric Test: Warm water. Brain interprets this movement as rotation of head to what side?

A

Same side

Ex. Right ear, right rotation

90
Q

Caloric Test: Warm water. Slow drift?

A

Contralateral

Ex. Right ear, left slow drift

91
Q

Caloric Test: Warm water. Fast drift?

A

Ipsilateral

Ex. Right ear, right fast drift

92
Q

Caloric Test: Warm water. Nystagmus

A

Ipsilateral nystagmus

Ex. Right ear, right nystagmus

93
Q

Caloric Test: Warm water. Patient falls to what side?

A

Contralateral

Ex. Right ear, falls left

94
Q

Caloric Test: Warm water. Patient past-points to what side?

A

Contralateral

Ex. Right ear, past-point left