Download Anatomy of the Ear

Anatomy of the Ear
Parts of the Ear
Outer Ear: From the
pinna to the
tympanic membrane.
Middle Ear: From the
tympanic membrane
to the end of the
stapes.
Inner Ear: From the
oval window to the
auditory nerve.
The Outer Ear
• The first part of the outer ear is the pinna or the
auricle.
• The purpose of the pinna is to collect and locate
sound.
Pinna
Crus of Helix
Concha
Lobule
The Outer Ear
• The external auditory
meatus is also known
as the Ear Canal.
• The purpose of the
external auditory
meatus is to channel
sound to the middle
ear.
• Cerumen or wax is
produced in this part
of the ear.
External Auditory Meatus
Tympanic Membrane
• The tympanic membrane is the dividing
point between the middle and outer ear.
• The tympanic membrane (TM) vibrates to
carry the sound to the middle ear.
• It is made of tissue similar to skin.
• The tympanic membrane is also called the
ear drum.
The Middle Ear
• The middle ear is an
air filled cavity.
• The ossicular chain is
the name for three
bones in the middle
ear used for hearing.
• The Eustachian tube
is also in the middle
ear.
The Ossicular Chain
• The ossicular chain, also called the ossicles, is a
series of three bones.
– Malleus, Incus, Stapes
• These bones are the smallest bones in the body.
• The bones are all connected.
– The TM vibrates the malleus and the sound energy
travels through the incus and the stapes. The stapes is
connected to the oval window.
The Ossicular Chain
Here are the bones in the ossicular chain. In the
ear they are connected.
The Eustachian Tube
• A tube that connects the middle ear to the
throat.
• The purpose is to regulate air pressure in
the ear.
• It allows fluid from behind the ear drum
to be discharged into the back of the nose.
The Inner Ear
• The inner ear is comprised of the cochlea,
and the semicircular canals.
• The stapes is connected to the oval
window.
– The oval window is the opening to the
cochlea.
• The cochlea is the organ used for hearing.
• The semicircular canals are used for
balance.
The Cochlea
• The cochlea is a snail-shaped organ filled with
tiny hairs used for hearing.
• It is connected to the auditory nerve.
Inside the Cochlea
• The cochlea is a long tube
curled up like a snail
shell.
• This tube is divided into
three sections.
• Each section is filled with
fluid.
• In the middle section, is
the Organ of Corti.
– This organ is the organ that
we hear with.
Organ of Corti
• This energy is transferred to the fluid.
• This fluid stimulates hairs on the Organ of Corti.
• This sends an impulse to the auditory nerve.
The Semicircular Canals
• The semicircular canals control balance.
Semicircular Canals
Oval Window
Cochlea
Round Window
Review
This picture demonstrates the chain of events that happens
when a sound is heard. Do not worry about the specific names.
Otitis Media
• Otitis Media, also known as an ear
infection, is a common infection of the
middle ear cavity.
• This happens when the Eustachian tube
becomes blocked and the middle ear
cavity becomes filled with fluid.
Otitis Media
• A doctor can tell if a person has otitis media by using an otoscope
to look down a person’s ear canal and looking at the tympanic
membrane.
• If the doctor sees the “cone of light” then the person’s ear is not
infected.
• If the doctor does not see the light and the tympanic membrane is
cloudy, the person probably has otitis media.
Otoscope
Cone of light
Healthy Tympanic Membrane
Otitis Media
Other Problems with the Ear
• Otolaryngologist
– Also known as an ear, nose, and throat (ENT)
specialist
– This doctor can diagnose problems that can occur in
the ear
– Some other problems besides otitis media are:
• Presence of foreign bodies
• Impacted cerumen (wax)
• External otitis (swimmer’s ear)
• Perforation of TM (tear in the TM)
• Otalgia (earache)
Describing a Hearing Loss
• There are three ways to categorize hearing
loss.
– Type
– Degree
– Age at Onset
Type of Hearing Loss
• There are three types of hearing loss.
– Sensorineural
– Conductive
– Mixed
• All three have an impact on a person’s
hearing.
• See page 7 in the course pack.
Conductive Loss
• A person has a conductive
loss if they have any problem
with the outer or middle ear.
– For example, if a person is
born without a pinna or if a
person has severe otitis
media.
• A conductive loss is almost
always “fixable.”
– Meaning that if you have
otitis media and you take
antibiotics then your
conductive loss will go away,
or if you born without a
pinna, you can have one
constructed.
The part of the picture
shaded in purple, shows
where a conductive loss is
located.
Sensorineural Loss
• A sensorineural loss is a hearing loss that
involves problems with the cochlea and/or the
auditory nerve.
– For example, sometimes the hairs in the Organ of
Corti are damaged, destroyed, or missing. This causes
a sensorineural hearing loss.
– The abbreviation often used for a sensorineural
hearing loss is SNHL.
– A sensorineural hearing loss cannot be “fixed.” It can
only be helped by hearing aids and cochlear implants.
Mixed Hearing Loss
• A mixed hearing loss is where a person
has both a conductive and a sensorineural
loss.
– For example, when a person has otitis media
and has damaged hair cells. This would cause
both a conductive and a sensorineural hearing
loss.
– When the person “fixes” the conductive
hearing loss, then the person just has a
sensorineural hearing loss.
Degree of Hearing Loss
• The degree of hearing loss
is determined by what a
person can or cannot hear.
• To determine this, a
person goes to an
audiologist and has a
hearing test done.
• The result of the test is
shown on an audiogram.
– An audiogram is a
visual representation
of a person’s hearing.
– An audiogram shows a
person’s “thresholds”
or the softest sound a
person can hear at
various frequencies.
Audiograms
• On the left side of the audiogram
is decibels (dB) or the loudness
of the sound.
• On the top is the frequency
which is measured in Hertz (Hz).
The frequency measures the pitch
of the sound.
• The markings for the right ear are
a red circle, O To remember this,
think red-right-round.
• The markings for the left ear are
blue X’s.
• Please see page 9 in your course
pack.
Degree of Hearing Loss
• Normal Hearing:
25 dB and below
• Mild Hearing Loss:
25-40 dB
• Moderate Hearing
Loss: 40-55 dB
• Moderately Severe
Loss: 55-70 dB
• Severe Loss:
70-90 dB
• Profound Loss: 90+
Degree of Hearing Loss
• Normal Hearing: 25 dB and below
• Mild Hearing Loss: 25-40 dB
• Moderate Hearing Loss: 45-55 dB
• Moderately Severe Loss: 55-70 dB
• Severe Loss: 70-90 dB
• Profound Loss: 90+
The specific numbers may vary. Different sources and
professions use different numbers. These are just one
set of numbers.
Age at Onset
• When a person acquires a hearing loss is
called the age at onset.
• There are two periods when this can
occur:
– Pre-lingual: Before language is developed
– Post-lingual: After language has developed
• Why do you think it is important as
teachers to know when your students
acquired their hearing loss?