Download Ears

Personal Health
Ears
Function

A. Function of ears is to gather sensory
information:
• 1. Sound waves for sense of hearing
• 2. Gravity and movement for sense of
balance.
Structure

1. The outer ear is also know as the
auricle.
• A. The external auditory canal goes through
•
•
the bone of the skull.
B. The canal is protected by tiny hairs and
glands that secrete wax.
C. The tympanic membrane (or the eardrum)
is at the inner end of the canal.

2. The middle ear has:
• A. Small bones called ossicles named for their
shape:
• Malleus(hammer), incus(anvil), and stapes(stirrup)
which is the smallest bone.
• B. The middle ear is drained by a oval
window.

3. The inner ear, or labyrinth, has three
important parts:
• A. The outermost, or cochlea, that turns
sound vibrations into nerve impulses.
• The path of sound waves in hearing is:
• 1. Enter the external auditory canal.
• 2. Eardrum vibrates.
• 3. Vibrations are carried across the middle ear by
the ossicles.
• 4. Travel through the inner ear.
• 5. Converted into nerve impulses.
• 6. Sent to the brain.
• The cochlear branch of the auditory nerve carries
impulses to the brain for interpretation as sound.
• In binaural hearing, brain notices differences in
loudness in each ear and can determine direction
from which sound came.

B. The central, vestibule, and innermost,
semicircular canals are responsible for
balance:
• Each canal has an organ called a crista with
•
•
hair cells in a fluid.
Gravity and movement cause hairs to move.
Nerves send information about body position
to brain and allow body to make adjustments
in balance.
Care of the Ears



1. Clean outer ears only with a cotton
swab.
2. Protect from cold.
3. Avoid loud noises by:
• Wearing ear protectors when operating loud
•
machinery.
Keeping volume low when listening to music.
Ear Problems


1. Deafness is a complete or partial
inability to hear.
2. Two kinds of deafness are common:
• A. Conductive deafness because sound
•
waves are not passed through ear properly.
Causes include:
• Buildup of fluid from ear infection, hardened wax
• Otosclerosis: a hereditary disorder in which an
overgrowth of bone causes the ossicles to lose
their ability to move.
• B. Sensorineural Deafness
• Sounds that reach the inner ear do not reach
•
the brain.
Damage to the cochlea, auditory nerve, or
part of the brain.
• Prolonged exposure to loud noise
• Certain types of medicines
• Increased fluid pressure in the labyrinth
• Viral infections
• Tumors

Tinnitus – a condition in which a ringing,
buzzing whistling, hissing, or other noise
is heard in the ear in the absence of
external sound.
• Overexposure to loud noise.