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EXCI 360 > Ch. 14: Vestibular System > Flashcards

Ch. 14: Vestibular System Flashcards

1
Q

What information does the vestibular system provide the CNS (4)?

A
  • Head movement and position
  • Gaze stabilization
  • Postural adjustments
  • Autonomic function and consciousness
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2
Q

True or false: The vestibular system can affect a person’s Blood pressure, can trigger dizziness and motion sickness

A

TRUE.

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3
Q

Which body system determines the position and motion of your head in space?

A

The vestibular system

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4
Q

What type of acceleration is it when you shake or nod your head?

A

Angular acceleration [ semi-circular canals]

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5
Q

What type of acceleration is it when detecting motion along a line?

A

Linear acceleration [Utricle and Saccule]

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6
Q

What TWO receptor organs (otolith organs) of the vestibular system are there to determine position and motion of a person’s head in space?

A

The UTRICLE and the SACCULE

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7
Q

The kinocilia of a group of hair cells are all located on what side of the hair cell?

A

The kinocilia of a group of hair cells are all located on the same side of the hair cell.

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8
Q

What is the receptor located at the base of the semi-circular canal called?

A

AMPULLA

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9
Q

What direction are the hair bundles in the ampulla?

A

The hair bundles are all in the same direction – and react the same: all on or all off.

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10
Q

When at rest are action potentials being sent to the brain via hair cells?

A

Yes. To a much lesser extent, but the hair cells are usually active

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11
Q

What direction is depolarization with hair cells?

A

Towards the kinocilia (long side)

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12
Q

When are the hair cells considered to be “on”?

A

When the stereocilia bind toward the kinocilia

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13
Q

When are the hair cells considered to be “off”?

A

When the stereocilia bind opposite the kinocilia

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14
Q

Where does the STRIOLA divide the hair cells into populations with opposing hair bundle polarities?

A

In the SACCULUS and UTRICLE, the striola divides the hair cells into populations with opposing hair bundle polarities.

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15
Q

What are Calcium carbonate crystals called?

A

OTOCONIA.

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16
Q

What are OTOCONIA (in the vestibular system)?

A

Calcium carbonate crystals

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17
Q

What can the degeneration of otoconia lead to?

A

BPPV: Benign paroxysmal positional vertigo

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18
Q

Which “hair bundles”, which project into a gelatinous layer of the OTOLITHIC MEMBRANE (sensory epithelium) of Utricle and Sacculus, are pointing TOWARD the STRIOLA in the UTRICULAR MACULA and AWAY from the STRIOLA in the SACCULAR MACULA?

A

The KINOCILIUM are pointed TOWARD the striola in the utricular macula and AWAY FROM THE striola in the saccular macula.

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19
Q

Explain what happens in the utricular and saccular maculae when the head is tilted.

A

The HAIR BUNDLES are deflected by the OTOCONIA (calcium carbonate crystals) in the direction of the gravitational force along the macular plane. one side will be inhibited while the group on the other side of the striola will be excited.

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20
Q

The kinocilia are directed toward/away from the striola and are more or less vertical and horizontal in the SACCULES, while in the UTRICLES the kinocilia oppositely are directed toward / away from the striola and are more or less vertical /horizontal.

A

The kinocilia are directed AWAY FROM the striola and are more or less VERTICAL in the SACCULES, while in the UTRICLES the kinocilia are directed TOWARD the striola and are more or less HORIZONTAL.

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21
Q

What will detect any movement of the head? Which macula will detect horizontal movement, and which up and down?

A

MORPHOLOGICAL POLARIZATION of hair cells in the utricular and saccular maculae. SACCULE UP AND DOWN / UTRICLE HORIZONTAL)

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22
Q

What is the STRIOLA?

A

The striola is a structural landmark consisting of small otoconia arranged in a narrow trench that divides each otolith organ.

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23
Q

Fill in the blanks:
The orientation of the h____ __ ___ (3 words) are organized relative to the s______ , which demarcates the overlying layer of o_______.

A

The orientation of the HAIR CELL BUNDLES are organized relative to the STRIOLA, which demarcates the overlying layer of OTOCONIA.

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24
Q

Forces acting on the head will displace what of the utricular macula?

A

Forces acting on the head displace THE OTOLITHIC MEMBRANE of the utricular macula.

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25
Q

When the head rotates, what distorts the cupula in the crista?

A

(ENDOLYMPHATIC) FLUID IN THE MEMBRANOUS CANAL distorts the cupula.

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26
Q

What is the cupula?

A

The cupula is found within the ampulla found at the base of each semi-circular canal. The cupula is a gelatinous mass containing HAIR CELLS which extends out of the CRISTA and bridges the width of the ampulla. The cupula creates a VISCOUS BARRIER that the ENDOLYMPH cannot penetrate / circulate. The acceleration forces the endolymph through which distorts/ displaces the cupula.

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27
Q

What is the function of the semicircular canals in the vestibular system?

A

Semi-circular canals detect rotational acceleration and deceleration from the head.

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28
Q

What type of cells are sensitive to “bending “ direction?

A

Hair cells are sensitive to bending direction.

29
Q

If a hair cell bends toward the kinocilium or opposite the kinocilium, the hair cell would be what?

A

The hair cells demonstrate excitation when bending TOWARD kinocilium and INHIBITION when bending OPPOSITE kinocilium.

30
Q

When turning the head quickly what is it that causes the endolymph to lag behind? And what does that do to the cupula / hair cells ?

A

Inertia causes the endolymph to lag behind in turn distorting the cupula and hairs of hair cell. Toward kinocilium ON opposite kinocilium OFF

31
Q

When turning head to the left. Which horizontal canal would be on and which would be off? Or would they both be off or on at the same time?

A

Turning head to the left – the left horizontal canal would be on (utricles, kinocilium toward striola) Right would be off.

32
Q

What are the arrangement of the semicircular canals in pairs?

A

The Right Superior canal –> Left Posterior canal
The Left Superior canal –> Right Posterior canal
Left Horizontal canal –> Right Horizontal canal

33
Q

What is the vestibulo-ocular reflex (VOR)?

A

A reflex, where activation of the vestibular system of the inner ear causes eye movement.

34
Q

What is the goal of the vestibulo-ocular reflex (VOR)?

A

To stabilize images on the retinas (when gaze is held steady on a location) during head movement by producing eye movements that counter head movements (allowing the gaze to remain fixed on a particular point)

35
Q

What type of movement will activate the vestibulo-ocular reflex (VOR)?

A

Horizontal and Lateral head movements.

36
Q

What happens if there is a loss of the vestibulo-ocular reflex (VOR)?

A

Oscillopsia (‘BOUNCING VISION’)
[Loss of the VOR can have severe consequences. A patient with vestibular damage finds it difficult or impossible to fixate on visual targets while the head is moving, a condition called oscillopsia (“bouncing vision”).]

37
Q

Is the vestibulo-Ocular reflex under voluntary control?

A

NO. With PASSIVE movement of a subjects head, the eyes should move in the opposite direction

38
Q

What are the two major cortical functions of the vestibular system?

A
  1. Spatial orientation

2. Self-motion perception

39
Q

What makes up the Central Vestibular system? (3)

A
  • 4 nuclei
  • 6 pathways
  • The vestibulocerebellum (eye movements and posture)
40
Q

What is the origin of the vestibulothalamocortical pathways?

A

The semi-circular canals.

41
Q

What do the vestibulothalamocortical pathways perceive?

A

Head orientation and movement/ eye movements

42
Q

There is a connection between semi-circular canals and eye movements via what nuclei?

A

The vestibular nuclei.

43
Q

What are otolithic organs comprised of?

A

Utricle and saccule.

44
Q

What do the otolithic organs perceive?

A

Head movements, postural control

45
Q

What are the 3 sensory systems that contribute to postural control?

A
  1. Somatosensory
  2. Vestibular
  3. Visual
46
Q

The SOT protocol is comprised of SIX Sensory conditions:

A
  1. Eyes - open, stable support, stable surround (All accurate)
  2. Eyes - closed, stable support (Vest./somato accurate – no vision)
  3. Eyes – open, stable support, sway surround (vest. / somato accurate – vision inaccurate)
  4. Eyes - open, sway support , stable surround (vest. / vision accurate – somato inaccurate)
  5. Eyes - closed, sway support (vest accurate – no vision, somato inaccurate)
  6. Eyes – open, sway support, sway surround (vest accurate, vision and somato inaccurate)
47
Q

When standing still, does our nervous system rely more heavily on vision or somatosensory info?

A

Somatosensory > vision for postural control information conditions 2 & 4

48
Q

When a person has a neurological lesion – which system do they rely predominantly on during the BEGINNING of their balance recovery?

A

VISION > somatosensory

49
Q

What index is given by the Sensory Organization Test system?

A

Sway Index – 0 standing still - no movement (not possible for human), 50 % is a lot of instability / sway – 100% = fall.

50
Q

In the Nashner postural study / aging, participants ≥ 65 years old were found to fall more often when during what TWO sensory conditions?

A

Condition 5 : No vision, inaccurate somatosensory and accurate vestibular.

Condition 6 : Inaccurate vision and somatosensory, accurate vestibular

51
Q

Can older adults perform double – legged stance using only one accurate sense?

A

Not very well

52
Q

Why are young adults significantly better at maintaining their balance using only one of three accurate senses?

A

Because YA’s vestibular system is better and can compensate for the lost senses.

53
Q

If vestibular system is damaged / lost - what happens when vision or vision and somatosensory is inaccurate?

A

The subjects will 100% FALL. No vestibular system – requires VISION and/or SOMATOSENSORY to maintain STANDING BALANCE

54
Q

What can cause disorders to the vestibular system (3)?

A
  • Disease
  • Aging (degeneration of vestibular system)
  • Injury
55
Q

What are the symptoms commonly associated with vestibular disorders (4).

A
  1. VERTIGO: Feeling of spinning or world around you spinning.
    a. Subjective vertigo: sensation of movement
    b. Objective vertigo: perception of movement in surrounding objects
  2. DIZZINESS: Feeling of being Lightheaded, woozy, unbalanced
  3. BALANCE AND SPATIAL ORIENTATION:
    i. Imbalance, stumbling, difficulty with coordination
    ii. Difficulty maintaining straight posture, need to see ground
    iii. Tendency to touch / hold onto something when standing
    iv. Difficulty walking in the dark
  4. VISION: Trouble focusing or tracking objects with the eyes; objects or words on a page see to jump, bounce, float, or blur etc. ex. NYSTAGMUS
56
Q

What is the pathology of benign paroxysmal positional vertigo (BPPV)?

A

Otoconia freed form macula float into semicircular canal (usually posterior) – with quick head movement, otoconia can fall to a new gravity dependent position. The movement of the otoconia produces abnormal fluid flow in semicircular canal – stimulating the hair cells in the cupula and creating abnormal signals in the vestibular nerve.

57
Q

What are the signs and symptoms of BPPV (6)?

A
  1. Vertigo – lasting more than 2 minutes provoked by moving head into specific positions.
  2. Brief interference with orientation and concentration (consciousness)
  3. Normal communication and memory
  4. Normal somatosensation (Sensory)
  5. Nausea (Autonomic)
  6. Poor balance and trouble walking (Motor)
58
Q

When does BPPV tend to occur?

A

Incidence of BPPV tends to increase with age

59
Q

What is the prognosis of BPPV?

A

90% of treated patients had full relief of symptoms.

60
Q

What happens during Canalithiasis?

A

In Canalithiasis, otoconia are detached from the macula and float freely in a semi-circular canal.

61
Q

What test is used to check for Canalithiasis or BPPV?

A

The Hallpike Maneuver

62
Q

How is the Hallpike maneuver performed?

A

By turning the persons head 45 ° to the right or left, then PASSIVELY moving the person from sitting to supine position with neck extended 30°. Each position is held for 1 to 2 minutes or until nystagmus and vertigo subside

63
Q

How does the Hallpike maneuver work?

A

The Hallpike maneuver tests for Canalithiasis by provoking maximal movement of the otoconia

64
Q

What is nystagmus?

A

Nystagmus is when your eyes are shifting from one area to another involuntarily. (semicircular canals are signaling head movement even though there is no movement)

65
Q

What is the Epley Maneuver and how does it work?

A

Canalith repositioning, like the Hallpike maneuver, the head is turned in different directions and held for 1 to 2 minutes or until nystagmus and vertigo subside. (The goal is for the otoconia to exit the semicircular canal)

66
Q

When the head is turned quickly to the RIGHT, which semicircular canal will there be an increase in vestibular nerve firing rates, and which canal will decrease in vestibular nerve firing rates?

A

When the head is turned to the RIGHT the afferent fibers of the vestibular nerve in the RIGHT semicircular canal will fire while the LEFT side decreases firing rates

67
Q

What is spontaneous nystagmus?

A

SPONTANEOUS NYSTAGMUS: The eyes move rhythmically from side to side in the absence of any head movements, occurs when one of the canals or nerves is damaged.

68
Q

What is one way to clinically produce the illusion of a right or left head turn?

A

Warm or cold H2O irrigation produces the illusion of a right or left head turn.

Warm H2O irrigation the endolymph rises in the horizontal duct which increases firing in the afferent nerve and turning the head to the irrigated side.

Using cold water irrigation would cause the opposite effect, the endolymph falls, decreasing the firing rate of the vestibular nerve and the head turns to the opposite side.

69
Q

What type of exercises are used for vestibular rehabilitation?

A

Exercises involving eye movement, head tilt, up and down body movement, walking with head turned. The goal is a progressive stimulation of the vestibular system during daily lie exercises and activities.

EXCI 360 (4 decks)

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