csdi 3105 hearing science exam 2

What is the problem addressed by the middle ear's polarization function?

It allows for the motion of cochlear liquids inside a closed capsule, enabling the traveling wave necessary for hearing.

What role does the round window play in the middle ear?

reciprocating motion that allows movement of cochlear liquids, causing wave action

What is the solution for ventilation and pressurization in the middle ear?

Opening the airway by the Eustachian tube during actions like swallowing, yawning, or chewing

Which muscles are involved in the opening of the Eustachian tube?

The tensor veli palatini and levator veli palatini muscles

Where is the opening of the eustachian tube?

Toros tubarius, in the nasopharynx

What is an eponym?

A proper noun (a person's name) that has become the name of a thing.

What is the primary purpose of the middle ear's protection function?

To reduce distortion and protect the inner ear from loud sounds.

How does the middle ear contribute to hearing?

Through impedance matching, polarization, ventilation, and protection, each addressing specific auditory challenges.

What is the role of the tympanic membrane in sound transmission?

It collects sound energy and transmits it to the stapes, increasing pressure at the oval window.

Who discovered the Eustachian tube and in what year?

Bartolommeo Eustachio discovered the Eustachian tube in 1561.

What is the primary function of the Eustachian tube?

To connect the middle ear to the nasopharynx for ventilation and pressure equalization.

What can Eustachian tube dysfunction lead to?

Lack of middle ear aeration, tympanic membrane perforation, otitis media, hearing loss, chronic tympanic membrane perforation, and cholesteatoma

What is cholesteatoma?

An abnormal skin growth in the middle ear that can destroy the ossicular chain and cause hearing loss, dizziness, and facial muscle paralysis

What are the four contributions of the middle ear to hearing?

1. Impedance-matching transformer function 2. Polarization function 3. Ventilation and pressurization 4. Protection and distortion reduction.

What problem does the middle ear protection function address?

Protecting the inner ear from mechanical over-stimulation

How does the acoustic reflex protect the inner ear?

By stiffening the ossicular chain through the action of the stapedius muscle, the sound intensity reaching the cochlea is reduced.

What triggers the acoustic reflex?

Stimuli such as eating, talking, yelling, and exposure to high-level sounds.

What is measured on the y-axis when assessing the acoustic reflex response?

Admittance or sound flow into the middle ear.

At what sound level is the acoustic reflex typically activated?

Around 90 dB HL.

What is the maximum benefit of the acoustic reflex for low frequencies?

20-30 dB loss.

What was the focus of the study by Borg et al. (1982) regarding stapedius reflex?

The fatigability of the stapedius reflex in industrial noise exposure.

What was observed in rabbits regarding middle ear muscles after industrial noise exposure?

The ear without functioning middle ear muscles had more hearing loss than the ear with functional muscles.

What effect does exercise have on the stapedius reflex according to Colletti et al. (1991)?

Exercise reduces the stapedius reflex and increases the risk of temporary threshold shift.

What is the significance of the acoustic reflex threshold?

It helps measure the function of the stapedius muscle and assess auditory disorders.

What is the definition of pathogenesis?

The mechanism that causes disease.

What is the definition of disease in this context?

A disorder of structure or function.

What is tympanic membrane perforation?

A hole in the tympanic membrane that can result from Eustachian tube dysfunction.

What is the role of the stapedius muscle in the acoustic reflex?

It stiffens the ossicular chain to reduce sound intensity entering the cochlea.

What is the auditory brainstem response used for?

To estimate hearing loss following exposure to industrial noise.

What action can reduce the stapedius reflex?

exercising depresses the stapedius reflex & increases risk of temporary hearing loss

Where are the tympanum & bony labyrinth located (in the skull)?

with the petrous portion of temporal bone

Which frequency region is found at the base of the basilar membrane?

20,000 Hz, High frequencies

Which frequency region is found at the apex of the basilar membrane?

200 Hz, Low frequencies

what is in the center of the cochlea?

the modiolus

Where does the oval window lead to?

scala vestibuli

where does the round window lead to?

scala tympani

what separates the scala vestibuli and the scala media?

reissner's membrane

what separates the scala media and the scala tympani?

basilar membrane

where is the organ of corti located?

It sits on top of the basilar membrane, in the scala media

what is the reticular lamina?

a thin layer of connective tissue that covers the tops of the hair cells

Which hair cells are pear-shaped & 95% afferent?

inner hair cells

Which hair cells are cylindrical-shaped & 95% efferent?

outer hair cells

Which of the hair cells have motility (they stretch & shrink)?

outer hair cells

How many rows of inner hair cells are there?

1 row

How many rows of outer hair cells are there?

3 rows

The stereocilia of these hair cells are NOT attached to the tectorial membrane, and in crescent shape. Which hair type of cells is it?

inner hair cells

The stereocilia of these hair cells ARE attached to the tectorial membrane and are W/V shaped. Which hair cells is it?

outer hair cells

Which hair cells have centralized nuclei?

inner hair cells

Which hair cells nuclei are found at the base?

outer hair cells

Where are the organelles of inner HC's found?

distributed through the cell body

Where are the organelles of the outer HC found?

along the outer walls

Where do the neurons of the inner hair cells synapse?

afferent neuron synapse w/ cell body & efferent synapes w/ the afferent neurons

where do the neurons of the outer hair cells synapse?

both afferent & efferent synapse directly w/ the cell body

What is the "stretching & shrinking" of outer HC's in response to efferent nerve stimulation called?

OHC motility

about how many inner HCs are there?

approx. 3500

about how many outer HCs are there?

approx. 12,000

How many OHC does type II fibers (inner radical fibers/IHCs) synapse w/ ?

up to 50 OHCs

Multiple type 1 fibers (outer spiral fibers/OHCs) synapse with how many IHCs?

with only 1 directly opposite of their habenular opening

What are the 3 features of the cochlea?

mechanical (vibratory), hydraulic (wave-motion) & chemo-electrical (nerve energy)

What is the bony labyrinth?

network of interconnected cavities within the temporal bone of the skull that protects and houses the structures of the inner ear

What is the membranous labyrinth?

fleshy tubes lining bony labyrinth, inside the bony labyrinth

what is the role of the semi-circular canals?

to sense movement of the head, both speed and direction

what are the parts of the vestibule

saccule and utricle

the utricle is ________ to the saccule

superior

what is the function of the utricle & saccule?

used to detect the orientation of the head, ex. if tipped up or down, or tilted to one side

What is the cochlea?

the fluid-filled, snail-shaped cavity of the inner ear, has 2 5/8th turns & the 8th nerve enter the center

what is the most anterior structure of the inner ear?

the cochlea

Describe the modilous

The center of the cochlea is spiral like a staircase, is what the bony canal turns around & the walls are solid bone

Which hair cells are the modiolus closest to?

the inner hair cells

What does the organ of corti contain?

inner and outer hair cells, the tectorial membrane, and sits on top of the basilar membrane

what discovered the organ of corti?

elfonso corti

where "scala" are the hair cells located?

scala media

What is the helicotrema of the cochlea?

the apex of the cochlea where the scala tympani and scala vestibuli meet

what is the fluid found in both the scala vestibuli & tympani?

perilymph

what fluid is found in the scala media?

endolymph

Where is the base of the cochlea?

near the stapes footplate

How long is the labyrinth (base to apex)

33mm, about 1 inch

What is the osseous spiral lamina?

Bony extension of the medial wall of the bony labyrinth, runs continuously along the medial wall "left handrail"

Where is the habenula perforata situated?

in the osseous spiral lamina

what is the spiral ganglion?

group of cell bodies located in the modiolus

Where is the 8th nerve located ?

internal auditory meatus/canal

does the width of the osseous spiral lamina decrease or increase between the base & apex of the cochlea?

it decreases, by the 3rd turn it has nearly disappeared

the inner hairs cells are _____ to the modiolus & spiral lamina

closest

What is connected to the inner & outer HCs?

neurons/nerve cells/nerve fibers

where are the HC's bodies located?

inside of the modiolus, the spiral ganglion

the scala vestibuli is bounded _______ by reissners membrane

inferiorly

the scala tympani is bounded _______ by the basilar membrane

superiorly

the width of the basliar membrane _______ between the base & apex of cochlea

increases

on which surface is the basilar membrane attached to the osseous spiral lamina?

its medial surface

What is tonotopic organization?

organization of sound frequencies in the basilar membrane, where different neurons respond to specific frequencies

The scala media is bounded superiorly by which membrane?

reissners membrane

the scala media is bounded inferiorly by which membrane?

basilar membrane

What is the habenula perforata?

The hole in the Osseous Spiral Lamina, which is a hole in the modiolus for the neurons that begin in the Scala Media to exit

how do the scala vestibuli & scala tympani share perilymph?

perilymph is shared at the helicomtrema

what keeps endolymph in the scala media?

Reissner's membrane

Basilar membrane

What attaches to the basilar membrane on its lateral surface?

spiral ligament

what attaches to the basilar membrane on its medial surface

osseous spiral lamina

what is the spiral limbus?

fibrous stiff cells on top of the osseous spiral lamina

what causes the basilar membrane to vibrate?

the stapes footplate moves the oval window, causing waves in the endolymph

where does endolymph come from?

stria vascularis