Anatomy and
Physiology of the
Ear
3 Parts of the Ear
Outer, Middle, and Inner Ear
• Part 1 OUTER EAR- Pinna to Tympanic
Membrane
The “pre amp” –makes sound waves stronger
Does Ear Wax Have a Purpose?
2 important functions
1.Keeps skin in ear canal
soft
2. Keeps bugs out 
(they don’t like the taste)
What Causes Outer Ear
Hearing Loss ?
• Wax pushed up against eardrum
(tympanic membrane)
from q-tip use 
• Sharp objects that puncture tympanic
membrane
• Born with damaged ear canal or
without pinna
• Swimmer’s Ear - what is that?
Swimmer’s Ear
• Water +
• Germs or bacteria +
• Wax in the auditory canal = mold 
• Complications
• How to treat it????
Tympanic Membrane
Healthy TM is translucent is
silvery in color
Red or pink or bulging shows
an infection.
TYMPANIC MEMBRANCE
Normal versus Infection
Part 2 - Middle Ear
• Sound waves change
to mechanical energy
in the middle ear
• ½” chamber
What are the parts of the Middle
Ear?
• Back of tympanic membrane
• 3 small bones
• Eustachian tube
Malleus, Incus, and Stapes
3 smallest bones in the body
Eustachian Tube
• What is the
purpose?
• Drain cells/tissue
• Equalize air
pressure
What Causes Hearing Loss in the
Middle Ear ?
• Calcium deposits on bones
Solution ?
• Loud sudden noises- firecracker, gunshot
Solution?
• Trauma to the head- fall, car accident
• Otitis media- what is that???
Otitis Media
• Most common ailment
for children- Why???
• Germs travel up
eustachian tube-lodge in
middle ear
Why are Parents concerned?
• Ossicles do not
vibrate correctly =
25dB hearing loss
• Critical time for
learning langauge
• Treatments??
Antibiotics
•
•
•
•
Children over medicated?
Will condition improve by itself?
Are new strains of bacteria developing?
Risks for developing speech?
Ear Tubes- Chronic Otitis Media
Small slit made in TM and tube put
in for drainage from Middle Earmost tubes fall out after a few
months
Which is your “real voice”?
• The voice YOU hear?
• The voice on a tape?
• Sorry- you’re the only
one who hears it
• Why?
• This is your voice to
the world 
CONDUCTIVE HEARING LOSS
• Any hearing loss occurring in the
OUTER or MIDDLE EAR
• Examples ?????
• Malformed pinna, too much wax,
swimmers ear (or water stuck in ear),
torn tympamic membrane, Otitis media,
calcium deposits on ossicles,
torn muscles that control the ossicles
Conductive Hearing Loss can be repaired
The Inner Ear
• Cochlea
• semi- circular canals
• auditory nerve (8th
cranial nerve)
• Note the changes of
energy as the sound
waves come through
each part of the ear
Entrance to the Inner ear
The 3 bones vibrate causing a
disturbance at the “Oval Window”
Parts of the Inner Ear
• Cochlea
• Semi-circular Canals
• Auditory (8th cranial) nerve
Why do you get dizzy?
• Liquid in Semi –
Circular canals
• Information from
cilia sent to brain
• Must match info
sent from eyes
• Dizzy = brain
doesn’t know
what to
follow
The COCHLEA
• Size of a pea
• Fluid –filled
• Contains up to 20,000
cilia or hair-like nerve
endings
• Movement of the fluid
stimulates the cilia
• Creates Electrical
impulses
Auditory nerve- carries electrical
impulses from cilia (in cochlea and
semicircular canals) to the brain for
interpretation
Sensorineural Hearing Loss
(Hearing loss in the Inner Ear)
Known etiologies• Multiple Sclerosis
• Leukemia
• Sickle cell
• syphilis
• Bacterial infection( meningitis)
• Mumps
• ototoxic drugs (aspirin)
• tumor (from cell phones?)
• noise explosion
• menieres disease
• genetic connexin 26
• toys- noise levels
• membrane rupture
• airbag (ruptures tympanic membrane, tinnitus hearing loss)
• Premature birth
• unknown
Review--Pathway of Sound
• Sound waves enter pinna travel through auditory canal
• Sound waves strike tympanic membrane causing vibrations
(mechanical energy)
• Vibrating TM causes ossicles to vibrate
• Vibrating stapes bone at oval window generates movement of
cochlear fluid (Hydralics)
• Fluid movement stimulates cilia- lined cochlea
• Cilia sends electrical impulses along auditory nerve to brain
for interpretation