12-4 Audition Flashcards

1
Q

A: In the OUTER ear the ___ & ______ direct sound/vibrations to tympanic membrane

B: Once in The MIDDLE ear _______ conduct sound from the tympanic membrane to the ___ _____

C: What does the EUSTACHIAN Tube do and where is it located?

A

A: In the OUTER ear the Pinna & [EAM Ear Canal] direct sound to the tympanic membrane

B: The MIDDLE ear [MIS ossicle bones]–>{Stapes/Incus/Malleus} conduct sound from the tympanic membrane to the [Oval vestibular window]

EAM = External Auditory Meatus

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2
Q

A: Cochlea

B: Perilymph [2]
ºsecreted by ___ ____ & __ ____
ºSimilar to __ fluid with ___(high/low) [Na+ and Cl- ]
ºFlows in [_____ duct] toward the _____ space
————————————————————————————–
————————————————————————————–
C: EndoLYMPH
ºSecreted by [__ ____] but requires ___ using ___ pump
ºUsually ___ (high/low) [Na+ and protein] and has net mV of ____
ºFlows in [____ duct] toward the __ ____ sac

D: Where are both of these located?

A

B: Perilymph =
ºsecreted by [scala tympani & scala vestibuli]
ºSimilar to interstitial fluid with high Na+ and Cl-
ºFlows in [perilymphatic duct]—>subarachnoid space
————————————————————————————–
————————————————————————————–
C: EndoLYMPH=
ºSecreted by [Stria Vascularis] but requires ATP using Na+/K+ pump
ºUsually low Na+ and protein with net mV of +80
ºFlows in [endolymphatic duct]—>[subdural endolymphatic sac] (where it’s reabsorbed into blood)
————————————————————————————–
D: BOTH IN INNER EAR

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3
Q

A: Sound Waves are made by ______

B: What is the Frequency auditory range for humans? What is Intensity based on?

A

A: Sound Waves are made by Air Pressure Oscillations above and below atmospheric pressure.

B: Freq. range of human auditory= 15Hz - 20kHz (BEST in 1-5 kHz). Intensity of Sound is based on Amplitude of Oscillations

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4
Q

A: How is the {L-shaped lever arm} of the Middle Ear Formed?

C: Where is the Tensor Tympani m. & what is it innervated by?

D: Where is the Stapedius m. & what is it innervated by?
D2: What is the OVERALL PURPOSE of these 2 Middle ear muscles?

E: What is the purpose of the [MIS Ossicle bones]

A

A: [Malleus] is attached to Tympanic Membrane on 1 end and then fuses with the [Incus] on the other= {L-shaped lever arm}

C: Tensor Tympani m.= Fast Striated m. (middle ear wall fibers) near eustachian tube that attaches to Malleus
{{Innervated by CN5B3}}

D: Stapedius m.= Fast Striated m. (middle ear wall fibers) tht attaches to [Stapes] near its connection with [Incus]
{{{Innervated by Facial CN7}}}

E: [MIS Ossicles bones] improve [air pressure oscillation TRANSFERENCE] from air —> [peri/endoLYMPH] by amplifying {air pressure oscillations} x20

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5
Q

A: [Bony Labyrinth] is the __-SHAPED CAVE of the ____ ear that surrounds a bony core called the _______. It’s housed in the ____ _______ bone and has a [_____ Snail Apex]. The [Bony Labyrinth] is divided into 3 canals.

B: These 3 Canals are separated by the ____ ___ _____ & ____ ___.

C: Describe These 3 Canals

A

A: [Bony Labyrinth] is the SNAIL-SHAPED CAVE of the INNER ear that surrounds a bony core called the [MODIOLUS]. It’s housed in the Petrous temporal bone and has a [Helicotrema Snail Apex]. [Bony Labyrinth] is divided into 3 canals.

B: 3 Canals: [Scala are separated by [Reissner’s Vestibular Membrane] & basilar membrane]
1. Scala Vestibuli (Contains perilymph & is continuous with bony labyrinth of vestibular apparatus)

  1. Membranous Labyrinth (inbetween 2 Scala)
  2. Scala Tympani (Contains perilymph and separated from Cochlear Duct by Basilar membrane in the round window)
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6
Q

A: [Membranous Labyrinth] is filled with ______ & forms the ___ ____ (or ___ ____) which contains [________]. This is where __________

B: How far does the Cochlear Duct extend throughout the cochlea in the [Membranous Labyrinth]?

C: In the [Membranous Labyrinth] what separates the Scala Vestibuli from Cochlear Duct ?

A

A: [Membranous Labyrinth] is filled with ENDOLYMPH & forms the COCHLEAR DUCT (or scala media) which contains [Organ of Corti]. This is where sound wave transduction—>nerve impulses occur.

B: Cochlear Duct extends throughout the cochlea, EXCEPT FOR HELICOTREMA

C: [Reissner’s Vestibular Membrane] separates Scala Vestibuli from Cochlear Duct

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7
Q

A: Sitting on the Basilar Membrane is the ______. This membrane Extends from _____ to ______

B: On the [Outer Cochlear DUCT Wall] you’ll find the ___ _____ which secretes _____ into _______ duct

A

A: Sitting on the Basilar Membrane is the [Organ of Corti]. This membrane Extends from [Spiral Lamina] to [Outer Cochlear Wall]

B: On the [Outer Cochlear DUCT Wall] you’ll find the [Stria Vascularis] which secretes endolymph into Cochlear DUCT

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8
Q

A: [Peri/endoLYMPH] are ____ fluids that when oscillated stimulate ___ ____ cells—>travel in ___ ___ ___
—->_______ into nerve impulses in the __ ___ ____

B: Describe the Flow of PeriLYMPH (3)

C: Describe the flow of endolymph (3)

A

A: [Peri/endoLYMPH] are cochlear fluids that when oscillated stimulate cochlear hair cells—>travel in cochlear nerve fibers—->vibrations into nerve impulses in the [Organ of Corti]

C: endolymph flows into membranous labyrinth of Vestibular Apparatus –>and then (via ENDOlymphatic Duct)—>subDural endolymphatic sac and reabsorbed into blood

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9
Q

1) The [Organ of Corti] contains __inner row and __ OUTER rose of hair cells. Describe each of these rows (OUTER vs. inner row)
2) What are Stereocilia
3) What supports these hair cells physically?

A

[Organ of Corti] contains 1 inner row and 3 OUTER ROWS of [hair cell cilia]
*OUTER ROW= insert into tectorial membrane & receive inhibitory inputs via olivocochlear n. fibers

  • inner row= move in endolymph between [Organ of Corti] and tectorial membrane –>TRANSDUCTS MOST OF SENSORY AFFERENT
  • 2) Stereocilia= [Tethered Hair cell cilia] arranged in a “V” and when 1 is bent –> causes neighboring Stereocilia to bend

3) Cuboidal & Columnar cells lie adjacent to these hair cells to support them

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10
Q

A: Inward & Outward Oscillatory movements of the ___ window are caused by __ __ __–> and result in opposite movements inside the ____ window. These Oscillations cause pressure to INC/DEC in [Scala Vestibuli]

B: Explain what Pressure change in [Scala Vestibuli] is transmitted to and How it gets there

C: How is a Tonotopic Map formed?

D: Where does this all occur?

A

A: Inward & Outward Oscillatory movements of the Oval window are caused by MIDDLE EAR OSSICLES–> and result in opposite movements inside the ROUND WINDOW. These Oscillations cause pressure to INC/DEC in [Scala Vestibuli]

B: Pressure change in [Scala Vestibuli]—>transmitted through [Reissner’s vestibular Membrane]—>[Scala Media Cochlear Duct]

C: Pressure change in [Scala Media Cochlear Duct] causes basilar membrane to move up and down —-> [TONOTOPIC MAP]

D: THIS ALL OCCURS IN THE COCHLEA

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11
Q

A: Depolarization is a function of _____ MEMBRANE movement. Oscillating movement of this membrane causes back&forth _____ movement of __ ___ ____

B: [___mV endolymph potential] and [___ mV intracell hair cell potential] –> ___ mV gradient across ____ hair cell = Normal Functioning

C: movement of inner hair cell cilia are amplified by what and how?

D: How does Hair Cells DEpolarize and Hyperpolarize?

E: What happens when a Hair cell DEpolarizes?

A

A: Depolarization is a function of BASILAR MEMBRANE movement. Oscillating movement of this membrane causes back&forth shearing movement of [stereocilia Hair cell cilia]

B: [+80 mV endolymph potential] and [-70 mV intracell hair cell potential] –> 150 mV gradient across apical hair cell = normal function

C: Movements of the inner hair cell cilia are amplified by OUTER HAIR CELLS which contract in phase with pressure oscillations

D:

  1. When Stereocilia are moved TOWARD kinocilia —>hair cell cilia K+ permeability INC = hair cell DEpolarizes
    - ————————————————————————————-
  2. When Stereocilia are moved away from kinocilia—>hair cell cilia K+ permeability decreases= hair cell hyperpolarizes

E: When DEpolarization occurs –> allows Ca+ into cells–> release of NTS glutamate–>causes depolarization (via [AMPA-type receptors]) of cochlear n. fiber–>INC action potential to CNS

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12
Q

Factors affecting freq. discrimination:

A: Hair Cell Cilia near Oval Window respond more to ____ frequencies and are __ in length. Why is this?

B: Hair Cell Cilia near helicotrema respond more to ____ freq and are ____ in length. Why is this?

A

Factors affecting freq. discrimination:

A: Hair Cells near Oval Window respond more to HIGHER freq. and are SHORTER in length –> this is becuz higher freq. transmit better thru the narrow stiff [basilar membrane] near Oval window

B: Hair Cells near helicotrema respond more to looowwerr freq. and are looonnger in length —> this is becuz this part of [basilar membrane] is wiiddder and more distensible

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13
Q

1) The Olivocochlear Efferent System ____ responses from selective ___ cells and consist of fibers from ___ and ______ nuclei .
This system makes _____ synaptic connections with ___ cells in ________ and ________

2) Which type of cilia are near the helicotrema and how is this related to frequency?

A

1) The Olivocochlear Efferent System ATTENUATES responses from selective hair cells and consist of fibers from both Contralateral and ipsilateral [SUP Olivary nuclei].
This system makes INHIBITORY synaptic connections with hair cells in [OUTER ROW—>controls amplifying effects] and [cochlear afferent terminals of inner row]

2) Longer cilia are near helicotrema and move better with loooowwwer freq.

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14
Q

Describe the Peripheral Auditory Pathway [2]

A

1) Bipolar neurons of [Spiral Ganglion] (located inside bony modiolus] send peripheral branches to innervate cochlear hair cells.
2) Central branches from [Spiral ganglion neurons] course thru [internal auditory canal] as afferent fibers in cochlear n.

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15
Q

•Cochlear nerve fibers enter brainstem at ___ _____ and terminate in ___________

B: Ventral cochlear nucleus is ___[smaller/Larger] and it projects to to the _______ nuclei in the _____. What is the TRAPEZOID BODY?

C: dorsal cochlear nucleus terminates in the ___ and ____ nuclei

D: [inferior Colliculus] relays ____ info (via ____) to_____ nucleus in the Thalamus —->sends ______ projections to _______ where it is interpreted

E: [T or F] Auditory Cortex is sensitive to lesions and can easily —> sound discrimination problems

A

•Cochlear nerve fibers enter brainstem at PONTOMEDULLARY JUNCTION and terminate in [Dorsal/Ventral cochlear nuclei]

B: Ventral cochlear nucleus is LARGER and it projects to ipsilateral & contralateral [SUP olivary nuclei] in Pons. **Midline crossing of these [Dorsal/Ventral cochlear nuclei] axons = TRAPEZOID BODY

C: dorsal cochlear nucleus terminates in the [inferior Colliculus] and [lateral lemniscus nuclei]

D: [inferior Colliculus] relays auditory info (via brachium) to [Medial Geniculate nucleus] in Thalamus —->sends auditory projections to [Area 41 Heschl’s Gyri]

E: FALSE! Auditory Cortex Lesions have to be EXTENSIVE in order to affect sound discrimination

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16
Q

A: Deafness is evaluated using _____ and ______testing with audiometry

B: Explain WEBER’S TEST [4]

A

B: WEBER’S TEST
1st: Tuning Fork placed on Skull midline

2nd: Normally sound is conducted simultaneously by both [ossicular air] and [bone] routes which are out of phase w/each other (1vibration up and 1vibration dwn)
3rd: Being out of phase—>Cancel each other out on both sides of head–>sound perceived as coming from midline
4th: If [ossicular air] route loses conduction, cancellation effect on that side is DEC and net vibration will be GREATER on the AFFECTED SIDE=AFFECTED SIDE hears sound louder

17
Q

Explain the Rinne Test [3]

A

1st: Place vibrating tuning fork on mastoid process of suspected side. Pt should hear vibrations in that ear = bone conduction route intact)
2nd: While tuning fork is still vibrating move prongs of fork to [outside ear pinna]–> where air conduction is 100x more sensitive than bone
3rd: Pt should still hear sound for 15 more seconds. If pt can’t hear sound for that long = air conduction deafness on that side

18
Q

ºIN Conduction deafness, a broad range of frequencies are lost but LOST OF ____ FREQUENCY is worst! IN Conduction deafness pt respond normally to bone ____ but have IMPAIRED ______ conduction responses

B: List 4 Causes of Conduction Deafness

C: What are 3 Treatments for this type of Deafness

A

ºIN Conduction deafness, a broad range of frequencies are lost but LOST OF LOWER FREQUENCY is worst! IN Conduction deafness pt respond normally to bone conduction but have IMPAIRED [OSSICULAR AIR] conduction responses

Causes:

1) Foreign objects in [EAM Ear canal]
2) Otitis media middle ear infections
3) Accumulation of [Cerumen Ear Wax]
4) Otosclerosis = Overgrowth of temporal bone around Oval window–>BLOCKS mvmnt of Stapes ossicle bone

Treatment:

  • Abx
  • Surgical Intervention for Otosclerosis
  • Hearing Aids to boost amplitude of sound
19
Q

What are the 4 types of Deaf Conditions

A
  1. Conduction Deafness
  2. Sensorineural
  3. Neural
  4. Central
20
Q

A: What are the signs/sx of Sensorineural deafness?

B: List 5 causes of Sensorineural deafness

A

Sensorineural deafness

A: loss of BOTH [ossicular air] AND bone conduction but higher frequencies are affected more = pt can’t understand constant sounds

B:

1) Hair cell damage
2) Chronic Loud Sounds above 4 kHz—> boilermaker’s dz
3) Aminoglycoside abs that accumulate in endolymph
4) Old Age AKA Presbyacusis {not corrctd by hearing aids}
5) antimalarial Quinine

21
Q

ººNeural deafness is characterized by _____ HEARING LOSS due to a lesion of the ____ nerve. Most common cause is __ ____ located in the __ __ ____and ___ ____

ºTreatment?

B: ºLesions at level of cochlear nuclei or auditory n. usually cause ____[unilateral/BiLateral] deafness

A

Neural deafness is characterized by UNILATERAL HEARING LOSS due to a lesion of the Auditory nerve. Most common cause is ACOUSTIC NEUROMA located in the [internal auditory canal] and [cerebellopontine angle]

Tx: Sometimes Surgical intervention

B: ºLesions at level of cochlear nuclei or auditory n. usually cause unilateral deafness

22
Q

1) What is Central Deafness caused by?

2)
ººUnilateral hearing loss from CNS lesions are _____ [common/rare] and why?
ºººLesions at level of __ ____or ___ ____usually cause unilateral deafness

3) “Auditory space” is associated w/__ ____ ____ ____
so auditory cortical lesion here means what for the pt?

A

1) Central Deafness is caused by a CNS lesion.

ºUnilateral hearing loss from CNS lesions are rare because there are multiple crossing of auditory pathways.

3) “Auditory space” is associated w/contralateral central auditory structures—>auditory cortical lesion here = pt can’t hear contralaterally