Lecture #4 - anatomy to hearing Flashcards
define hearing :
sense through which spoken langueage or non-speech sounds are received, transmitted and processed by auditory system
what are the two systems o fthe auditory system ?
peripheral and central auditory system
what is the peripheral auditory system ?
outer ear to auditory nerve
what is the central auditory system ?
beyond the auditory nerve to cerebral cortex
what are the four parts of the peripheral auditory system ?
- outer ear
- middle ear
- inner ear
- auditory nerve
what are the two key components of the outer ear ?
pinna & external ear canal
what are the four key components of the middle ear?
- middle ear cavity
- tympanic membrane (eardrum)
- ossicles
- eustacian tube
what is another word for “ossicles” ?
bones
where are the ossicles found ? (which part of ear)
contained within the middle ear cavity
what are the ossicles connected to ?
the eardrum
how many ossicle bones are there ?
3
what are the three ossicle bones ?
- malleus
- incus
- stapes
which bone can also be called “hammer” ?
malleus
what do the ossicles bones work together to create ?
a chain
FILL IN THE BLANK
the malleus, incus and stapes bridge between the ____________ & ___________
eardrum and inner ear
what is the malleus attached to ?
the tympanic membrane
what is the smallest bone in the body ?
the stapes
what could damage to the stapes do ?
damage to this bone may cause partial or complete hearing loss
out of all ossicles bones which is the biggest ?
malleus
how big is the malleus ?
around 9 mm
what do the malleus and incus work together to create ?
a lever to tranfer force (soundwaves) to the inner ear
what bone attaches to the tympanic membrane ?
the malleus
what do the ossicles transmit ?
sound vibrations from the eardrum to the inner ear
where specifically in the inner ear do the ossicles bridge between ? (from the eardrum to the ______ )
oval window
what is another term of the incus ?
anvil
how big is the incus ?
around 7 mm
what is the incus attached to ?
the head of the malleus
how is the incus attached to the malleus ?
via tissue (saddle joint)
how does the incus move ?
moves together with the malleus a lever
what is another term for the stapes ?
stirrup
what does the stapes do ?
takes soundwaves and converts it to mechanical energy
how big is the stapes ?
around 3 mm long and 1 mm wide
where does the stapes attaches ?
to the incus
what is the stapes footplate ?
- is the flat, bottom part of the stapes bone
what does the stapes footplate connect ?
connects to the oval window, a membrane-covered opening that leads to the inner ear
how are the ossicles held in place ?
by muscles and ligaments
what specific muscles help hold the ossicles in place ?
- tensory tympani muscles
- stapedius muscle
where does the tensory tympani muscles attach ?
attached to malleus from the front wall
where does the stapedius muscle attach ?
attached to stapes from the back wall
what do muscles protec the inner ear from ?
damage
what is “accoustic reflex” ?
involuntary muscle contractin that occurs in the middle ear in response to loud sounds
an accoustic reflex involves the contraction of what two muscles ?
tensory tympani muscles and stapedius muscles
the tensory tympani muscles and stapedius muscles act on what ?
the ossicles
what does an accoustic reflex protect us from ?
really loud sounds
what is the ear’s way of protecting themselves ?
an accoustic reflex
how does an accoustic reflex work ?
1) when a loud noise hits your ear, it triggers tiny muscles in your middle ear to tighten
2) these muscles pull on the small bones (ossicles) that help transmit sound, making them less able to move
3) by stiffening these bones, the reflex reduces the amount of sound sent to your inner ear, helping protect it by damage
physiologically, what does the middle ear function as ?
functions as transformer
what does the middle ear do ?
converts sound energy to mechanical energy
what are the 5 steps that allow the middle ear to convert sound energy to mechanical energy ?
1) siund waves vibrate tympanic membrane
2) tymoanic membrane moves malleus
3) malleus transmits vibrations via incus to stapes
4) stapes movement vibrates oval window
what is the “oval window” ?
its the middle ear’s openinig to the inner ear
what does the middle ear do in regards to pressure ?
boosts pressure from tympanic membrane to oval window
why does the middle ear boost pressure from tympanic membrane to oval window ?
- the middle ear boosts pressure to make sure sound vibrations can move from the air (in the ear) to the fluid (in the inner ear)
if the middle ear didn’t boost pressue going into the inner ear, what would happen ?
without this boost, sound would lose strength when moving from air to fluid, making it harder to hear
where is the pressure higher ? stapes or eardrum ?
pressure at stapes is 20X that at the eardrum
where is the eustachian tube located ?
between the middle ear cavity and the pharynx
describe an adults eustachian tube :
- 35 mm
- 45 degree downwards
- less prone to infections
describe a young childs’ eustachian tube :
- around 17 mm
- nearly horizontal
- prone to infections
describe an infants eustachian tube :
- shorter
- wider
- most prone to infections
when does the eustrachian tube open ?
when pressure is applied
what are some examples of when pressure may be applied to the eustrachian tube ?
- yawning
- swallowing
- sneezing
is the eustrachian tube usually open or closed ?
normally closed
when does the eustrachian tube open ?
1x/minute while awake
1x/5 minutes while asleep
what tube runs from your middle ear to your throat ?
eustachian tube
what are the 3 main functions of the eustrachian tube ?
- protects middle ear
- aerates middle ear
- drains middle ear
how does the eustachian tube protect the middle ear ?
- equalizes pressure with the outside and within
- keeps the tympanic membrane flexible
how does the eustachian tube aerates the middle ear ?
air from pharynx to middle ear
how does the eustachian tube drain the middle ear ?
fluid from middle ear infections
what happens if the eustachian tube is blocked ?
air can’t move between the middle ear and the throat, which causes pressure to build up in the ear (negative pressure)
what might you feel if your eustachian tube is blocked ?
- discomfort
- muffled hearing
- ear pain
- even infections because fluid can get trapped in the middle ear
what happens anatomically if the eustachian tube is blocked (negative air pressure) ?
negative air pressure → eardrum retracts → eardrum becomes stiff → decreased hearing of low frequency sounds
what happens anatomically if the eustachian tube is blocked (persistent negative air pressure) ?
middle ear cavity fills with fluid → eardrum bulges → increased eardrum stiffness → decreased hearing of low and high frequency
what happens anatomically if the eustachian tube is blocked (persisent middle ear fluid) ?
persistent middle ear fluid → ottis media → can become infected → ruptured eardrum
when are we more at rise of reprtured eardrum ?
when our eustachian tube is blocked / negative pressure
what are the two most common consequences of blocked eustracian tube ?
retracted eardrum and bulging eardrum
what is another word for Eustachian tube ?
auditory tube
where is the inner ear housed within ?
the tempral bone
what does the inner ear connect to ?
nerve impulse
what is the role of the inner ear ?
to convert mechanical energy into nerve impulses (electrochemical signal) to be sent to brain
what two things specifically are the inner ear responsible for ?
balance and equilibrium
TRUE OR FALSE
the inner ear is a motion-sensitive system
TRUE
is the inner ear fluid or not ?
up until the inner ear it is not fluid filled, then once it its the inner ear everything is fluid-filled
what part of the ear is responsible for motion (e.g., head movement, sound, gravity) ?
inner ear
what is the vestibule ?
the central part of the inner ear that helps with balance
what does the vestibule connect ?
the middle ear to the inner ear
what is the very first entry point into the inner ear ?
the vestibule
what are the 3 key components of the inner ear ?
- vestibular appartus
- cochlea
- auditory nerve
what is the role of the vestibular apparatus ?
maintain balance and position in space
what is the role of the cochlea ?
hearing
what is the role of the auditory nerve ?
info about hearing and balance up to the brain
what does the vestibular appartus look like in the inner ear ?
loops at the top
what does the cochlea look like in the inner ear ?
a snail
what does the auditory nerve look like in the inner ear ?
the larger tube exiting the ear
what are the two parts of the vestibular appartaus ?
semicircular canals and vestibule
what is the first section of the inner ear ?
vestibular appartus
what part of the inner ear detects change in gravity ?
vestibule
what part of the ear has the ability to say if were upright/our position ?
vestibule
damage in what part of ear can lead to vertigo ?
vestibule
what is vertigo ?
dizzineses
what part of the vestibular apparatus is the “entry way into system” ?
vestibule
what part of ear senses where our body is in space ?
vestibule
what part of the ear is known as the “organ of hearing” ?
cochlea
describe the anatomy of the cochlea
hard-walled, fluid-filled chamber in coiled/shell shape
how many openings does the cochlea have ?
2
what are the two cochlea openings covered by ?
membrane
what are the two openings of the cochlea called ?
- oval window
- round window
what are some functions of the cochlea ?
- tranduces the sound waves into electrical signal
- translates the inner ear
what attaches to the oval window ?
the stapes bone
TRUE OR FALSE
only the oval window is responsible for communication in the inner ear
FALSE
both openings are responsible for commuincation in the inner ear
how many compartments are there in the cochlea ?
3
what are the three componets of the cochlea ?
- upper
- lower
- middle
what do compartments 1 and 2 contain ?
perilymph fluid
where do we find the organ of corti ?
in the cochlea
what is the organ of corti ?
the thing converting mechanical energy waves to sound energy
what makes the organ of corti special ?
- contains special sensory cells called hair cells, which convert sound vibrations into electrical signals that are sent to the brain
- these signals help us hear
what type of fluid does compartment 3 (middle) contain ?
- super thick fluid that we dont have anywhere else in the body
- “endolymph”
what type of fluid does compartment 1 and compartment 2 contain ?
perilymph
what does the basilar membrane within the cochlea help us with ?
helps us detetct hearings and different frequencies
describe the structure of the basilar membrane in the cochlea :
- runs the length of the cochlea (base to apex)
- around 36 mm long
- covered by tiny hair cells (cilia)
what is the function of cilia ?
helps us precieve sound
what do auditory nerve endings help us connect to ?
hair cells
describe the row of hiar cells in the basilar membrane :
one row of inner and three rows of outer hair cells
what is the structure of the cochlea basilar membrane ?
varies in width across chamber of cochlea
what are the two parts of the cochlea (basilar membrane) ?
apex and base (near stapes)
whats more stiff; the base or apex ?
base is narrower and 100x stiffer
what’s less stiff; the base or apex ?
apex less stiff
what is the main functions of the cochlea (basilar membrane) ?
helps turn sound into signals for the brain. It moves with sound vibrations, and different parts react to high or low sounds, triggering hair cells to send hearing signals to the brain
how does the fluid move in the basilar membrane in cochlea ?
fluid moved by motion of stapes at oval window
what happens to cilia as fluid moves across the membrane ?
as fluid moves across the membrane, cilia are bent
TRUE OR FALSE
stimulates specific place on basilar membrane based on frequenecy
TRUE
TRUE OR FALSE
place of maximum vibration on basilar membrane determines sound frequency
TRUE
TRUE OR FALSE
In the cochlea, different areas can respond to the same pitches: high-pitched sounds activate one part, and low-pitched sounds activate that same part. This organized layout helps the brain identify different sound frequencies.
FALSE
In the cochlea, different areas respond to different pitches: high-pitched sounds activate one part, and low-pitched sounds activate another. This organized layout helps the brain identify different sound frequencies.
WHAT is tonotopic organization ?
is how sounds are arranged by pitch in parts of the ear or brain
in regards to tonotopic organization, 1000-20,000 Hz represents closests to what part of the cochlea ?
closest to the base
in regards to tonotopic organization, 20-100 Hz represent closests to what part of the cochlea ?
represented near the apex
define the “base” of the cochlea :
The base is the part closest to the middle ear, and it responds to high-pitched sounds
define the “apex” of the cochlea :
The apex is the tip or end of the cochlea, and it responds to low-pitched sounds. This arrangement is part of the cochlea’s tonotopic organization
what type of pitched sounds are near the apex ?
LOW pitched
what part of the cochlea responds to motion ?
organ of corti
what type of pitched sounds are near the base ?
HIGH pitched
what is the end organ of hearing ?
organ of corti
where is the origan of corti located ?
sits on top of basilar membrane
what does the organ of corti convert ?
converts mechanical sound energy into electrical impulse
describe the steps of the physiology of the inner ear :
- stapes moves oval window
- causes fluid displacement within cochlea
- moves basilar membrane (depends on frequency of sound wave it detects
- creates shearing motion of hair cell cilia
- motion translates by receptor cells into electrochemical signal (organ of corti)
- carried by auditory nerve fibers to brain
what is another term for auditory nerve?
vestibulocochlear
what is the last part of the peripheral auditory path ?
auditory nerve
how many afferent connections (sensory, ascending) does the auditory nerve have from the inner hair cells and vestibular system?
30,000
what are the two parts that the auditory nerve has afferent connections from ?
1) inner hair cells
2) vestibular system
where does the auditory nerve terminate (end) ?
at cochlear nucleus in brainstem
what does the central auditory system allow ?
allows binaural representation of sound
how does the central auditory system have sound localization ?
by comparing information from both ears
what part of the ear is the ascending binaural pathways found ?
central auditory system
what system does the following apply to ?
Ascending binaural pathways :
- right and left ear inputs
- contralateral and ipsilateral connections
central auditory system
how does the central auditory system work ?
- connects the ear to the brain
- after sound signals travel through the auditory nerve, they reach the brainstem
- from there, the signals go to different parts of the brain, like the thalamus and the auditory cortex
- the system helps the brain figure out what you’re hearing by organizing, interpreting, and making sense of the sound signals sent from your ears
describe the parts of the body in the central auditory system :
cochlea to the → auditory nerve → this sends impulses to the → brainstem → are then processed and passed to the brain → signals go to thalamus → then send finally to the → auditory cortex
describe the main function of the cochlea in the central auditory complex :
Sound vibrations are turned into electrical signals by the hair cells inside the cochlea
describe the main function of the auditory nerve in the central auditory complex:
these signals are sent through the auditory nerve, which acts like a messenger that carries sound information from the cochlea to the brain
describe the main function of the brainstem in the central auditory complex:
once the signals reach the brainstem, they are processed and passed to higher parts of the brain. The brainstem helps figure out things like the direction and timing of the sound
describe the main function of the thalamus in the central auditory complex:
the signals go to the thalamus, which is like a relay station; It sends the sound information to the auditory corte
describe the main function of the auditory complex :
this is where sound is fully processed and understood, allowing you to recognize voices, music, and other sounds
where is the auditory complex located ?
in the brain
how does hearing happen ?
sound waves go from the outer ear → middle ear → inner ear → auditory nerve → brainstem → cortex
which of the following :
- outer ear
- middle ear
- inner ear
- auditory nerve
- brainstem
- cortex
falls under “transformation” ?
middle ear
which of the following :
- outer ear
- middle ear
- inner ear
- auditory nerve
- brainstem
- cortex
falls under “transduction” ?
- inner ear
- auditory nerve
- brainstem
- cortex
which of the following :
- outer ear
- middle ear
- inner ear
- auditory nerve
- brainstem
- cortex
falls under “transmission” ?
outer ear
which of the following is NOT a bone in the middle ear ?
a) malleus
b) cochlea
c) incus
d) stapes
b) cochlea
what is the primary function of the ossicles in the middle ear ?
a) to convert sound waves into electrical energy
b) to amplify and transmit sound vibrations from the eardrum to the inner
c) to regulate the pressure in the inner ear
d) to produce sound
b) to amplify and transmit sound vibrations from the eardrum to the inner
which of the following structures connects the middle ear to the throat and helps equalize air ?
a) eustachian tube
b) oval window
c) round window
d) semi-circular canals
a) eustachian tube
the smallest bone in the human body is the :
a) malleus
b) incus
c) stapes
d) cochlea
c) stapes
which structure vibrates in response to sound waves and transmits vibrations to the ossicles ?
a) oval window
b) tympanic membrane
c) round window
d) eustachian tube
b) tympanic membrane
where does the eustachian tube connect ?
a) the middle ear to the inner ear
b) the middle ear to the nasopharynx
c) the outer ear to the middle ear
d) the cochlea to the brain
b) the middle ear to the nasopharynx
what is the primary function of the eustachian tube
a) to amplify sound vibrations
b) to convert sound waves into electrical signals
c) to qualize air pressure between the middle ear and the atmosphere
d) to transmit sound vibrations to the cochlea
c) to qualize air pressure between the middle ear and the atmosphere
if the eustachian tube is not functioning properly, what common symtpom might occur ?
a) dizziness
b) hearing loss
c) ringing in the ears
d) ear ache
d) ear ache
what is the primary function of the cochlea ?
a) to maintain balance
b) to convert sound vibrations into neural signals
c) to regulate air pressure in the middle ear
d) to transmit sound waves to the outer ear
b) to convert sound vibrations into neural signals
which structure in the inner ear is responsible for detecting rotational movements of the head ?
a) cochlea
b) utricle
c) semicircular canals
d) saccule
c) semicircular canals
the vestibular system is primarily involved in :
a) hearing
b) developing sound waves
c) converting mechanical energy
d) balance and spacial orientation
d) balance and spacial orientation
what is the function of the hair cells in the cochlea ?
a) to produce sound
b) to detect sound vibrations and convert them into electrical signals
c) to maintain balance
d) to regulate fluid pressure in the inner ear
b) to detect sound vibrations and convert them into electrical signals
which type of fluid is found within the cochlear duct ?
a) perilymph
b) endolymph
c) plasma
d) cerebrospinal fluid
b) endolymph
what is the primary function of the basilar membrane ?
a) to convert sound waves into electrical signals
b) to amplify sound vibrations
c) to seperate the scala vestibuli from the scala tympani
d) to determine the frequency of sound waves
d) to determine the frequency of sound waves.
