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
Outer ear (external)
• Auricle or Pinna
- This is the visible part of the ear.
2) The auditory canal
- 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, incus- anvil, 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
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
• Ear
• Cochlea
• Auditory
Nerve
• Brain
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Transformer
Analyzer
Conductor
Receiver
Match the following words with the
correct term
• Ear
• Cochlea
• Auditory
Nerve
• Brain
•
•
•
•
Transformer
Analyzer
Conductor
Receiver
Ear
Conductor
Receiver
Auditory Nerve
Cochlea
Transformer
Brain
Analyzer
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 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
small bones of the middle ear)
(eardrum,
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.
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
– Slideshow:
• http://www.nlm.nih.gov/medlineplus/tutorial
s/hearingloss/htm/_no_50_no_0.htm