Parts and Functions of the Ear

What is sound?

• Sound is the vibration of air molecules. Sound waves refer to the “ripples” created as the sound vibrations move out from the source.

The hearing mechanism

Regions of the ear

a. The pinna

The function of the pinna is to capture sound waves.

g. The auditory canal

The auditory canal has two functions:

• 1. To send sound waves to the middle ear.

• 2. To keep the ear clean of debris.

a) cilia: hair

b) cerumen: ear wax

f. The Tympanic Membrane

The tympanic membrane has two functions:1. Seals off the middle ear.

2. Vibrates the ossicles (ear bones).

The ossiclesthe three smallest bones in the

body• h. Malleus

(hammer)• i. Incus

(anvil)• j. Stapes

(stirrup)• (MIS)

Ligaments connect the malleus directly to the back of the tympanic membrane.

The stapes taps the cochlea to transmit sound vibrations to the inner ear.

e. Eustachian tube• Has two functions:• Equalizes air pressure in the

middle ear• Drains the middle ear

b. semicircular canal c. cochlea

• The semicircular canals maintain balance.

• The cochlea changes sound vibrations to nerve impulses.

The cochlea is spiral, hollow chamber of bone filled with liquid and thousands of nerve endings.

These nerve endings are triggered

by vibrations sent through the liquid-filled cochlea. As the nerves exit the cochlea they combine together to become the auditory nerve.

d. The auditory nerve

The auditory nerve is a collection of nerves sending nerve impulses to the brain.