The Ear

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The Ear
The ear is the sensory organ that
allows us to hear. It converts airborne
sounds waves into nerve impulses that
are decoded by the brain
Parts of the ear
1) Outer ear (external)
• Auricle or pinna
• The auditory canal
• This is the visible part of the ear
• It gathers sound waves from the environment and
directs them along the auditory canal
– is 3.75 cm long
– Has walls lined with hairs and glands that
secrete wax  these prevent foreign particles
from entering the ear
– Ends at the tympanic membrane or eardrum
2) The middle ear
• The eardrum or tympanic membrane
• Three small bones or ossicles (maleus -hammer, incusanvil, stapes- stirrup)
• It is linked to the Eustacian tube which serves to
equalize the air pressure on the two sides of the eardrum
3) The inner ear
• a fluid filled cavity in the temporal bone
• Contains the semicircular canals and the cochlea
For your information
http://video.about.com/pediatrics/Ear-Pressure.htm
The takeoff or landing of an airplane, the acceleration of
an elevator, deep-sea diving, or driving up a steep hill in
a car all bring about changes in air pressure which may
be experienced as discomfort in the ears. This feeling is
the result of increased pressure being exerted on the
eardrum, which causes it to bulge on one side or the
other, depending where the pressure is higher. Usually
the act of yawning, swallowing, or sneezing opens the
Eustachian tube, equalizing the pressure on the two
sides of the eardrum and relaxing this membrane.
Cochlea
• spiral-shaped
• fluid-filled inner ear structure
• lined with cilia (tiny hairs) that move when
vibrated and cause a nerve impulse to form
• The axons of cilia form the auditory nerve that
sends auditory signals to the brain
• http://www.youtube.com/watch?v=-WA7-k_UcWY
Match the following words
with the correct term
• Ear
• Cochlea
• Auditory
Nerve
• Brain
•
•
•
•
Transformer
Analyzer
Conductor
Receiver
Hearing & the ear
This is the chain reaction which takes place in the
hearing process:
(put the following words in the appropriate order)
sounds waves
hearing
Vibration of the eardrum
auditory canal
center for hearing in the brain
the auricle
three bones of the middle ear
nerve impulse is triggered in the auditory nerve
cilia move (inside cochlea)
Chain Reaction of Hearing
sound waves  the auricle  the auditory canal 
vibrations  the eardrum  the three bones of the
middle ear  cilia move (inside cochlea)  nerve
impulse is triggered in the auditory nerve  the center
for hearing in the brain  hearing
Hearing loss & prevention
• Hearing loss: the total or partial
inability to hear sound in one or both
ears.
• Preventing hearing loss is more
effective than treating it after "the
damage is done."
• True or False Quiz:
http://www.hearingcenteronline.com/factfic.shtml
Hearing loss and prevention
• 3 Main causes of hearing loss:
1. Partial or total blocking of the auditory canal by wax
Hearing loss & prevention
• 3 Main causes of hearing loss:
2. Rupture of the eardrum
Ear Drum or
Tympanic
membrane
Hearing loss & prevention
• 3 Main causes of hearing loss:
1. Ear wax
2. Rupture of the eardrum
3. Loss of sensitivity of the
mechanical structures
(eardrum, small bones of the middle ear)
Otitis
• Inflammation and/or infection of the middle ear
• Acute otitis media (acute ear infection) occurs
when there is bacterial or viral infection of the
fluid of the middle ear, which causes production
of fluid or pus.
• Chronic otitis media occurs when the eustachian
tube becomes blocked repeatedly due to
allergies, multiple infections, ear trauma, or
swelling of the adenoids.
Hearing loss & prevention
• Guidelines to maintaining
good hearing:
A.Removing wax
B.Be careful when diving
C.Avoid high pitched sounds
D.Avoid loud sounds
• Wear protective ear wear (plugs, muffs, etc.)
COCHLEAR IMPLANTS
Surgery videos
• TYMPANIC MEMBRANE SURGERGY
• http://www.entusa.com/surgery_videos.htm
Review Questions
1)
2)
3)
4)
5)
6)
7)
What part of the ear gathers sound
waves in the air?
What name is given to the structure that
connects the ear to the nose?
How does the ear protect itself from
unwanted incoming particles?
What two structures compose the inner
ear?
What structure contains the hearing
receptor cells?
Which part of the ear houses the nerve
endings for hearing?
When does a person experience the
sensation of hearing?
1)
What part of the ear gathers sound waves in the air?
- The auricle or the pinna
2)
What name is given to the structure that connects the
ear to the nose?
- Eustacian tube
3)
How does the ear protect itself from unwanted
incoming particles?
- The ear wax that lines the auditory canal
4)
5)
6)
7)
What two structures compose the inner ear?
- The semicircular canals and the cochlea
What structure contains the hearing receptor cells?
- The cochlea
Which part of the hearing system houses the nerve
endings for hearing?
- The auditory nerve
When does a person experience the sensation of
hearing?
- When the temporal lobe of the brain receives nerve
impulses from the auditory nerve
Internet resources
• Meniere’s disease (loss of balance):
• http://www.nlm.nih.gov/medlineplus/ency/ar
ticle/000702.htm
• Slideshow:
• http://www.nlm.nih.gov/medlineplus/tutorial
s/hearingloss/htm/_no_50_no_0.htm

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