12-4 Vestibular Flashcards Preview

NEUROLOGY > 12-4 Vestibular > Flashcards

Flashcards in 12-4 Vestibular Deck (19):
1

A: Equilibrium is Maintained and Controlled by what 3 sensory inputs? How many is needed to maintain Balance

A: Equilibrium is Maintained and Controlled by
1. Vestibular apparatus of internal ear
2. Vision
3. Proprioreception
[It only requires 2 out of the 3! to maintain Balance]
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2

A: What are the Sx[4] and Causes of Vertigo?

B: What are the Sx[3] and Causes of Meniere's Dz?

Vertigo Sx: Dizziness, Nausea, Vomiting and Pallor
Vertigo Causes: Labyrinthine irritation
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Meniere's Dz= Recurrent vertigo with tinnitus & deafness

3

The [Bony Labyrinth] is a continuous system of _______ in the _______ Bone. It is filled with (______-like) _______.

vs.

Membranous Labyrinth which is a system of _____ _____ that fit "hand to glove" with the twist of the ____ _____. ML is filled with intracellular-like {__rich _____}

B: [Stria Vascularis] in the _____ duct produces _____

The [Bony Labyrinth] is a continuous system of cavities in the [Petrous Temporal Bone] filled with extracellular-like PERILYMPH.

vs.

Membranous Labyrinth which is a system of interconnected TUBES that fit "hand to glove" with the twist of the [Bony Labyrinth] ML is filled with intracellular-like {K+ rich ENDOLYMPH}

B: [Stria Vascularis] in the cochlear duct produces ENDOLYMPH

4

A: Vestibular Hair cells are _____ _____ _____ located in the _____ of Semicircular Canals AND _____ of the [Utricle & Saccule].

B: Kinocilium = _____ cilium arising from a _____.
- Movement of bundled Stereocilia toward it= _____
-Mvmnt AWAY from Kinocilium = _____

C: Tilting the head causes the [_____ membrane] to slide and inertia will displace _____ cells. Displacing these cells allow _____ , ______and _____ detection

D: [_____ membrane] is similar to the [CUPULA] of the [Crista ampullaris]. It is made by Stereocilia of [_____ & _____] and contains [_____] which also add weight

A: Vestibular Hair cells are [bundled stereocilia mechanoreceptors] located in the [Crista Ampulla] of Semicircular Canals AND Maculae of the Utricle & Saccule.

B: Kinocilium = single long cilium arising from a centriole.
- Movement of bundled Stereocilia toward= Depolarization
-Mvmnt AWAY from Kinocilium = HYPERpolarization

C: Tilting the head--> [otolithic membrane] to slide and inertia displace [bundled Stereocilia hair cells] ---->Allows gravity, acceleration and position detection

D: [Otolithic membrane] is similar to the [CUPULA] of the [Crista ampullaris]. It is made by Stereocilia of Utricle & Saccule and contains [Ca+carbonate Otolithic granules] which also add weight

5

A: _____ hair cells of the [Crista ampullaris] produce a gelatinous [_____] to cover and protect them.

B: How are the Semicircular Canals paired up?

A: Stereocilia hair cells of the [Crista ampullaris] produce a gelatinous [CUPULA] to cover and protect them.

B: ANT canal is parallel to POST canal from other side. Horizontal canals from both sides form functional pair together

6

A: Where is the [Scarpa's Vestibular ganglion] found and what type of neurons is it?

B: How do Primary Vestibular Afferents get to the [Vestibular Nuclei Complex]?
**Primary Vestibular Afferents Enter __ ___ as _____ at the
_____ junction--->then courses between __ and ____ to get to _____ or few to the________

C: [Vestibular Nuclei Complex] are found in the _______ extending from __ to ____. What are the 4 Vestibular nuclei?

A: [Scarpa's Vestibular ganglion] is found in the [internal auditory meatus] and made of bipolar neurons

B: Primary Vestibular Afferents Enter brain stem as [CN8-vestibular division] at the Pontomedullary junction--->then courses between [inf cerebellar peduncle] and [spinal trigeminal nucleus] to get to [Vestibular Nuclei Complex] or few to [Flocculonodular lobe] of cerebellum

C: [Vestibular Nuclei Complex] are found in the [4th Ventricle Lateral Recess] extending from Obex to [CN6 abducens nucleus]
[Vestibular Nuclei Complex];
1.Deiter's lateral
2. medial
(3). SUP and inf vestibular nuclei

7

A: How does [Vestibular nuclei complex] coordinate with the Cerebellum Flocculonodular lobe? What does this do for the VNC?

B: Flocculonodular lobe participates in controlling _______ muscles associated with _______ AND ALSO controls _____ movements and coordination of _____& ______ movements together.

A: [Cerebellar Vermis] connects [Vestibular nuclei complex] to the (Flocculonodular lobe---> [Cerebellar fastigial nucleus] )
--->gives [VNC] info about skeletal muscle posture/spinal cord status

B: Flocculonodular lobe participates in controlling postural muscles associated with balance AND controls eye movements and coordination of [head & eye ]movements.

8

Describe the 3 Vestibulospinal Tracts

1. Lateral vestibulospinal tract Arises from [_____ nucleus] & descends ___ to ___ spinal cord levels to activate _____

2. MEDial vestibulospinal tract is the MAJOR component of ___ __ and comes from [_____ nucleus] . Projects to ___ spinal cord levels to innervate ______

3. Spinovestibular tract

1. Lateral vestibulospinal tract
Arises from [lateral vestibular nucleus] & descends ipsilaterally to ALL spinal cord levels to activate EXTENSOR motor neurons

2. MEDial vestibulospinal tract
is the MAJOR component of DESCENDING MLF and comes from [medial vestibular nucleus] . Projects to CERVICAL spinal cord levels to innervate neck muscles

3. Spinovestibular tract = collaterals of spinoCEREbellar projections

9

ASCENDING Medial Longitudinal Fasciculus (MLF)
1. Arises from what 2 nuclei?

2. Describe where it projects to?

3. what is its purpose?

4. Explain how CROSSED Ascending MLF Fibers are different than UnCrossed Ascending MLF Fibers?

**ASCENDING Medial Longitudinal Fasciculus (MLF)**
1. Arises from [medial vestibular nuclei] and [SUP vestibular nuclei]

2. Projects BILATERALLY to CN3, 4 and 6's nucleus!

3. Coordinates [conjugate Eye mvmnts] (via reticular formation) with Head mvmnt (i.e. vestibuloocular reflex)

4.
***CROSSED Ascending MLF = EXCITES XtraOcular m.
vs.
*inCrossed Ascending MLF= inhibits xtraocular m.

10

Describe The interactions between the Thalamus and the Vestibular system [3]

1. Vestibulo-thalamic projections aren't well described

2. [Ventral POST thalamic nucleus] relays vestibular info to area of parietal cortex behind the primary sensory cortex

3. General Equilibrium perception (so may be linked to vertigo)

11

A: Vestibular efferents are typically considered _____ reflex pathways with _____[Much/little] "big-brother" cortical control. What does this mean for the Vestibular Reflex?

B: You can voluntarily move your eyes but MOST eye mvmnt are _____. What 4 Areas contribute to eye movement?

A: Vestibular efferents are typically considered INDEPENDENT reflex pathways with LITTLE cortical control = it's hard to voluntarily stop vestibular reflex

B: You can voluntarily move your eyes but MOST eye mvmnt are REFLEXIVE. Areas contributing to eye movement:
*Retina
*SUP colliculus
*cerebral cortex & cerebellum

12

A: [SUP colliculus] contains neurons that respond to ______and functions to _______. It receives MANY afferents from ____, _____ and ______

B: The Orienting "startle" response by the [SUP colliculus] is mediated by ____ and _______ projections

C: Lesioned [SUP colliculus] will lead to what?

D: How is the [SUP colliculus] related to Saccades

A: SUP colliculus contains neurons that respond to MOVING Visual Stimuli and functions to adjust movements of our head/eyes toward that MOVING stimulus. It receives MANY afferents from RETINA, [inf colliculus] & cerebral cortex.

B: The Orienting "startle" response by the [SUP colliculus] is mediated by tectospinal and tectoreticular projections

C: Lesioned [SUP colliculus] =inability to Orient to moving visual stimuli

D: [SUP Colliculus] can initiate/control Saccades

13

A: Frontal eye fields are located in the __ __ ___ and are considered the _______. Frontal eye fields influence ____ nuclei using ___ and ____

B: Lesioned [Frontal Eye Fields] will lead to what?

A: Frontal eye fields are located in the MIDDLE FRONTAL GYRUS and are considered the [center for Voluntary eye Saccades]. FEF influence Ocular nuclei using [SUP colliculus] and PPRF

B: Lesioned FEF ---->inability to look contralaterally (with reflex eye movements intact)

14

A: Occipital eye fields are in the __ lobe and project to the __ ____to ________
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B: Saccades are ___________ toward ______ objects in the visual field. Saccades are controlled by __ or ____ and it ___ vision during mvmnt. How does Head turns play a role in Saccades?

A: Occipital eye fields are in the Occipital lobe and project to [SUP colliculus] to promote eye movements in response to visual inputs
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B: Saccades are Voluntary, RAPID Eye Turns toward peripheral objects. Saccades are controlled by [SUP colliculus] or [Cerebral Cortex] and it blurs vision during mvmnt. (Head turns AFTER the Saccade
--->OPPOSITE compensatory eye mvmnt

15

A: Tracking/Smooth Pursuit involves _____ using ______. Is Tracking/Smooth Pursuit voluntary and can it be done without Visual Stimuli?

B: What is the [Fixation Reflex]? Give example

C: [Optokinetic Railway Nystagmus]? Give example

A: Tracking/Smooth Pursuit involves "Locking" eyes onto perceived moving object using [Occipital Eye Fields]. Although These mvmnts are voluntary, smooth sweep of eyes CAN'T be done in ABSENCE of visual stimuli

B: Fixation Reflex = same as smooth pursuit mvmnt but allows us to fix on an object when BOTH person AND object are moving [Ex: Reading road sign while driving on bumpy road]

C: [Optokinetic Railway Nystagmus] = (to-and-from) oscillating eye mvmnts made when ur fixating on moving objects [Ex: Looking @ telephone pole out window of moving train]

16

1. What is Vergence?

2. What is it controlled by?

1. Reflex convergence/Divergence of eyes in order to focus on objects getting closer/Further from u
2. Controlled by [Occipital projections] to [SUP colliculus}

17

Nystagmus are __ ___ ___ that have both _ and __ components (but during test refers to ___ component only) *There are 3 types*

1. SPONTANEOUS Nystagmus is ____[sometimes/always] pathological and is caused by ___ ____ 2º to ______
What are the 4 sx?

vs.

2. [Induced Postrotatory Nystagmus of Barany] = ______ which causes ______ and thus Nystagmus

3. [Induced CALORIC Nystagmus] is when irrigation of the ____ ___ ____with warm/Cold water creates___ _____ in the ____ _____. This as a result stimulates ______ by ______

B: What does Cold water do vs. warm water?

C: What does the [Induced CALORIC Nystagmus] test for?

Nystagmus are OSCILLATING EYE MOVEMENTS that have both slow and Fast components (but during test refers to Fast component only) .

1. SPONTANEOUS Nystagmus is ALWAYS PATHOLOGICAL and is caused by [Vestibular imbalance] 2º to irritating or destructive lesions. Sx= N/V, [bp DEC] & Tachycardia
vs.
2. [Induced Postrotatory Nystagmus of Barany] = Rotation of body sets endolymph in motion--->causes deflection of stereocilia hair cells

3. [Induced CALORIC Nystagmus] is when irrigation of the [External Auditory Canal] with warm/Cold water creates convection currents in Vestibular labyrinths--->stimulates [crista ampullaris] by deflecting stereocilia

B: COWS =
Cold Water--->Eyes move opposite direction of irrigation
warm water -->eyes move in same direction of irrigation

C: test function of individual semicircular canals (ESPECIALLY HORIZONTAL CANAL)

18

Vestibular nuclei:
**There are four divisions of the vestibular nuclei

Lateral: [receives afferents from ______ and ______) is concerned with ______ (______ muscles) and
[vestibulo-ocular reflex] (via ____).
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Medial & Superior: [receives afferents from ______ and ______ ] = concerned with ______ and ______
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Inferior : [receives afferents from ______, ______ AND ______] = projects to ______, and works to ______

Vestibular nuclei:
**There are four divisions of the vestibular nuclei

Lateral: [receives afferents from utricle and saccule) is concerned with posture (extensor muscles) and vestibulo-ocular reflexes (via MLF).
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Medial & Superior: [receives afferents from Utricle and Semicircular Canals] = concerned with vestibulo-ocular reflexes and coordination of eye & neck muscles.
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Inferior : [receives from Utricle, SCC AND Saccule] projects to cerebellum, and coordinates balance with voluntary movements.

19

What are the 3 ways we can get "Dizzy"?

1. Vestibular input without vision (i.e. spinning in a chair with eyes closed--> constant motion that eventually results in cupola membrane returning to its baseline)

2. [Motion detection from Visual system] but WITHOUT [Vestibular confirmation] (looking out car window when an adjacent car moves away= false sense of motion)

3. [Motion detection from Vestibular system] but WITHOUT [Visual confirmation] (sitting in cabin of a boat during a storm= MOTION SICKNESS)