12-4 Vestibular Flashcards
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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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
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
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
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
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
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.
Describe the 3 Vestibulospinal Tracts
- Lateral vestibulospinal tract Arises from [_____ nucleus] & descends ___ to ___ spinal cord levels to activate _____
- MEDial vestibulospinal tract is the MAJOR component of ___ __ and comes from [_____ nucleus] . Projects to ___ spinal cord levels to innervate ______
- Spinovestibular tract
- Lateral vestibulospinal tract
Arises from [lateral vestibular nucleus] & descends ipsilaterally to ALL spinal cord levels to activate EXTENSOR motor neurons - 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 - Spinovestibular tract = collaterals of spinoCEREbellar projections
ASCENDING Medial Longitudinal Fasciculus (MLF)
1. Arises from what 2 nuclei?
- Describe where it projects to?
- what is its purpose?
- 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]
- Projects BILATERALLY to CN3, 4 and 6’s nucleus!
- Coordinates [conjugate Eye mvmnts] (via reticular formation) with Head mvmnt (i.e. vestibuloocular reflex)
- **CROSSED Ascending MLF = EXCITES XtraOcular m.
vs. - inCrossed Ascending MLF= inhibits xtraocular m.
- **CROSSED Ascending MLF = EXCITES XtraOcular m.
Describe The interactions between the Thalamus and the Vestibular system [3]
- Vestibulo-thalamic projections aren’t well described
- [Ventral POST thalamic nucleus] relays vestibular info to area of parietal cortex behind the primary sensory cortex
- General Equilibrium perception (so may be linked to vertigo)
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
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
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)
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?
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
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]
- What is Vergence?
2. What is it controlled by?
- Reflex convergence/Divergence of eyes in order to focus on objects getting closer/Further from u
- Controlled by [Occipital projections] to [SUP colliculus}
Nystagmus are __ ___ ___ that have both _ and __ components (but during test refers to ___ component only) There are 3 types
- 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) .
- SPONTANEOUS Nystagmus is ALWAYS PATHOLOGICAL and is caused by [Vestibular imbalance] 2º to irritating or destructive lesions. Sx= N/V, [bp DEC] & Tachycardia
vs. - [Induced Postrotatory Nystagmus of Barany] = Rotation of body sets endolymph in motion—>causes deflection of stereocilia hair cells
- [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)
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
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.
What are the 3 ways we can get “Dizzy”?
- 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)
- [Motion detection from Visual system] but WITHOUT [Vestibular confirmation] (looking out car window when an adjacent car moves away= false sense of motion)
- [Motion detection from Vestibular system] but WITHOUT [Visual confirmation] (sitting in cabin of a boat during a storm= MOTION SICKNESS)
