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Warm-up!!
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 – temporary hearing loss, long-term infection, deep tissue infection, bone & cartilage damage, further infection
• How to treat it: antibiotics or antifungals, ear drops, steroids (for inflammation)
Tympanic MembraneHealthy 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: surgery to remove the stapes bone
• Loud sudden noises- firecracker, gunshot
Solution?
• Trauma to the head- fall, car accident
• Otitis media – “middle ear infection”
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
language
• Treatments usually
include antibiotics and
occasionally ear drops.
• Sometimes repeated ear
infections can result in
tubes being put in ears.
Ear Tubes- Chronic Otitis Media
Small slit made in TM and tube put
in for drainage from Middle Ear-
most tubes fall out after a few
months
CONDUCTIVE HEARING LOSS
Any hearing loss occurring in the OUTER or MIDDLE EAR
• Malformed pinna
• too much wax
• swimmers ear (or water stuck in ear)
• torn tympanic 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 (Hydraulics)
• Fluid movement stimulates cilia- lined cochlea
• Cilia sends electrical impulses along auditory nerve to brain for interpretation