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