Lecture 14: Vestibular and Auditory Systems Flashcards by Katlyn Heneghan

Which part of the ear contains petrous portion of temporal bone, bony labyrinth, and membranous labyrinth?
A. Outer Ear
B. Inner Ear
C. Middle Ear

B. Inner Ear

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True or False: The Membranous Labyrinth contains perilymph

False - the bony labyrinth does!

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True or False: The Inner Ear serves both hearing and equilibrium

True

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Membranous labyrinth consists of ____ and ____ ___

Vestibule
A. Saccule
B. Urticle

Semicircular canals

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What is the function of the vestibule (saccule + urticle)?
A. Detects motion
B. Detects linear acceleration

B. Detects linear acceleration

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True or False: The saccule has the macula in its FLOOR while the utricle has the macula in its LATERAL WALLS

True

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Which of the following parts of the vestibule detects up and down movement of the head, as well as forward and backward?
A. Saccule
B. Utricle

A. Saccule

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Which of the following parts of the vestibule detects side to side movements of the head (linear acceleration in lateral plane)?
A. Saccule
B. Utricle

B. Utricle

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Detection of hair cells during head movements causes firing of ____

Action Potentials

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Which two structures are embedded in the otolithic membrane?

Crystals
Hair cells

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True or False: When head moves, this leads to crystals of the ear moving, which leads to matrix movement, hair cell deflection, then nerves firing

True

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True or False: The Vestibule is responsible for detecting angular acceleration and head rotation

False - the Semicircular ducts do this!

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How many ducts are located in the body semicircular canals?

Three

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____ is the dilated end of the semicircular duct
A. Kinocilla
B. Ampulla
C. Cillia
D. Endolympth
E. Crista Ampullaris

B. Ampulla

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Within the semicircular ducts, there is the ampulla (dilated end of duct). Within the ampulla, there is ____, which is the sensory end organ containing hair cells
A. Kinocilia
B. Crista Ampullaris

B. Crista Ampullaris

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How are the stereocilia of the ampulla arranged?
A. graduated rows
B. graduated columns
C. no specific arrangement

A. graduated rows

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Which of the following is the LONGEST true cilium found in the ampulla of the semicircular ducts?
A. Kinocilium
B. Crista Ampullaris
C. Cupula

A. Kinocilium

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True or False: Kinocilia of the hair cells in any given crista are oriented in DIFFERENT directions

False - kinocilia of hair cells in any given crista are oriented in the SAME direction

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True or False: Kinocilia of hair cells in the horizontal ducts are oriented VERTICALLY

false - toward midline

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True or False: There are three semicircular ducts (anterior, posterior, and horizontal) -
Each is positioned at right angles to each other and work in pairs

True

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True or False: When one moves their head, endolymph move in the same direction

False - moves in opposite direction

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When one moves their head, it deflects the kinocilium toward midline, leading to AP firing of ___ fibers

afferent

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What decreases firing rate of AP’s?
A. Deflection of kinocilium towards midline
B. Kinocilium moving away from midline

B. Kinocilium moving away from midline

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Movement of ____ causes deflection of kinocilia and neuron firing

endolymph

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Sensory nerves are located in vestibular ganglion, also known as ____ _____

Scarpa's Ganglion

Ganglion cells are bipolar. Where does the peripheral process synapse?

Receptor hair cells

True or False: The vestibulocochlear nerve attaches to the brainstem at the potomedullary juntion in the pontocerebellar angle

True

The central axonal process of the ganglion cell will project ipsilaterally to which two structures?

1. Vestibulocerebellum (maintains equilibrium and coordinates eye movements with head, neck, and body) 2. Vestibular Nuclei

True or False: There are 4 vestibular nuclei - superior, inferior, medial, and lateral

True

Vestibular afferents terminate in ipsilateral ____ ____

vestibular nuclei

The Lateral Vestibular Nucleus gives rise to Lateral Vestibulospinal Tract (LVST). What does it innervate? What is its function?

Innervates: extensor musculature Function: maintains balances/allows for postural changes

The Medial Vestibular Nucleus gives rise to the Medial Vestibulospinal Tract. What does it innervate? What is its function?

Innervates: neck musculature Function: stabilizes head

Which of the vestibular nucleus give rise to cerebellar afferents that project to the vestibulocerebellum? A. Medial vestibular nucleus B. Lateral vestibular nucleus C. Superior vestibular nucleus D. Inferior vestibular nucleus

C. Superior vestibular nucleus D. Inferior vestibular nucleus

True or False: The vestibular nuclei also project to contralateral paramedian pontine reticular formation

True

Nystagmus -- involuntary eye movements -- has slow and fast components. Always named for direction of ___ one

fast

Under what conditions can nystagmus be physiological?

Large rotations of head Vestibular activation

True or False: Under physiological conditions, SLOW component of nystagmus is OPPOSITE to direction of head turning while FAST component is IN DIRECTION of head turning

True

True or False: If nystagmus occurs spontaneously, it is sometimes pathologic

False - it is ALWAYS pathological

What causes clinical nystagmus?

Lesion ETOH CNS Disorders Toxicity

What is common finding in VS disorders?

Nystagmus

True or False: Vertigo may be due to central or peripheral lesions

True

_____: Illusion of movement of body or environment; associated with nystagmus, nausea, vomiting

Vertigo

True or False: Most cases of vertigo are caused by peripheral lesions, associated with inner ear (75%) while central lesions are associated with brainstem or cerebellum (25%)

True

For sound, the lower the pitch, the ___ the frequency; the higher the pitch, the ___ the frequency

lower; higher

The bony cochlea is part of the ___ labyrinth while the cochlear duct is part of the ____ labyrinth

bony; membranous

____: A bony tube that winds spirally 2 and 3/4 turns around central pillar of bone (modiolus) A. Cochlear Duct B. Bony Cochlea ______: part of the membranous labyrinth, it enter bony cochlea and is attached at end to two side of the cochlea A. Cochlear duct B. Bony Cochlea

B. Bony Cochlea A. Cochlear duct

The cochlear duct divides cochlea into two, long spiral chambers: ___ (above cochlear duct) and ____ (below cochlear duct)

1. Scala vestibuli 2. Scala tympani

Scala vestibuli and scala tympani communicate with each other at the apex of the modiolus via a small opening known as the ____

Helicotrema

What are scala vesibuli and scala tympani filled with? A. Perilymph B. Endolymph

A. Perilymph

How does sound get from the external auditory meatus to the oval window?

External Auditory Meatus => Ear drum => Ear ossicles => Oval window

Bony Cochlea and Cochlear duct make up the A. Middle Ear B. Outer Ear C. Inner Ear

C. Inner Ear

What is the Floor boundary of the cochlear duct? Roof boundary?

Roof: vestibular (Reissner's) membrane Floor: basilar membrane

The organ of hearing (Organ of Corti) lies on the ____ membrane

basement membrane

The Organ of Cori is composed of hair cells. The inner hair cells form a __ row while outer hair cells form ___ rows

single; 3

The Organ of Cori has free surface of hair cells, which are covered with ___ but no ___

stereocilia; kinocilium

Where in the cochlea is the spiral ganglion located?

Within modiolus of cochlea

Does the spiral ganglion mostly innervate inner or outer hair cells?

Inner - 90% innervate inner hair cells - 10% innervate outer hair cells

The cochlear nerve and nuclei are central processes of the spiral ganglion that forms the cochlear nerve and terminates in the ___ and __ cochlear nuclei

ventral/dorsal

Airborne sound waves strike the tympanic membrane, which vibrates in response. How are vibrations transmitted across tympanic caivty?

Three bony ossicles

The foot plate of the ___ moves to and from in the oval window, transmitting vibration to fluid-filed inner ear

stapes

How is the pressure from the compression of perilymph released?

Round window

Pressure waves start in perilymph, result from oscillations of foot plate of stapes. Pressure waves enter ___, then helicotrema, then ____

scala vestibuli; scala tympani

True or False: Pressure waves transmitted through endolymph of cochlear duct makes basilar membrane vibrate

True

The basilar membrane near the BASE of the cochlear vibrates preferentially to sounds of ____ Basilar membrane near the APEX of the cochlea vibrates preferntially to sounds of ____

high pitch/freq low pitch/freq

True or False: Oscillations of basilar membrane cause deflection of hair cell sterocilia, thereby opening ion channels and causing cells to release NT at synapse that trigger AP

True

True or False: Superior olivary cells are sensitive to differences in time of arrival of auditory stimuli from both ears

True

Which order neurons project bilaterally to the superior olivary complex?

2nd

True or False: Cochlear nuclei are organized tonotopically

True

Where are the dorsal/ventral cochlear nuclei located? Where is the superior olivary complex located?

medulla pons

____ is the first point in the auditory pathway that input from both sides converge

Superior olivary complex

Cells in the superior olivary complex send axons through the lateral lemnisci to terminate at the ____ ____

inferior colliculus

___ ____: Receives afferents from ipsilateral lateral lemniscus A. Superior olivary complex B. Inferior Colliculus C. Medial Geniculate Nucleus

B. Inferior Colliculus

Inferior colliculus sends fibers to ipsilateral MGN (medial geniculate nucleus) via the brachium of ___ ____

inferior colliculus

_____: Located deep within lateral fissure; also known as transverse temporal gyrus of Heschl (Brodmann's Area 41 and 42) A. Auditory Association Cortex B. Primary Auditory Cortex C. Medial Geniculate Nucleus D. Inferior Colliculus

B. Primary Auditory Cortex

______: Located in posterior 2/3 of superior temporal gyrus (area 42 and 22). In dominant hemisphere, it is largely synonymous with Wernicke's Area. A. Auditory Association Cortex B. Primary Auditory Cortex C. Medial Geniculate Nucleus D. Inferior Colliculus

A. Auditory Association Cortex

If sound vibrations do not reach the oval window, what type of hearing loss occurs? A. Sensorineural hearing loss B. Conductive hearing loss

B. Conductive hearing loss

True or False: Sensorineural hearing loss is caused by disease of the cochlea, cochlear division of CN VIII, or cochlear nuclei in the medulla

True

Otosclerosis (fixation of the foot plate of the stapes), otitis media, or excess cerumen can cause which type of hearing loss?

Conductive Hearing Loss

Prolonged exposure to loud noise, Toxic side effects from pharmaceuticals, and Acoustic neuroma can cause which type of hearing loss?

Sensorineural