THE EAR
The ear is an organ of hearing and balance. Its functions are made possible by various parts in it.
Parts of the ear
The ear is divided into mainly three parts: outer ear, middle ear and inner ear. The outer ear consists of:
pinna, external auditory canal and tympanic membrane. The middle ear consists of; ossicles and
Eustachian tube while the inner ear consists of; cochlea, vestibule and semicircular canals.
The outer ear
Pinna: this is the visible part of the ear. Its purpose is to catch sound waves, amplify them and funnel
them down to the eardrum.
External auditory canal: this is the tube that connects the outer ear to the middle ear.
Tympanic membrane(eardrum): the tympanic membrane is a very thin structure that divides the outer
ear from the middle ear.
The middle ear
Ossicles: consists three small bones that are connected and transmit the sound waves to the inner ear.
The bones are; malleus, incus and stapes. The oval window membrane is one of the two membranes
that separate the middle ear space from the inner ear. The other is the round window membrane.
Eustachian tube: this is a canal that links the middle ear with the back of the bone. It helps to equalize
the pressure in the middle ear which is necessary for proper transfer of sound waves.
Inner ear
Cochlea: consists of hearing nerves. Has sensory hair cells which convert the mechanical energy from
the vibrations of the basilar membranes into electrical impulses.
Vestibules: this contains receptors for balance
Semicircular canals: contains receptors for balance
How exactly does hearing occur?
When a sound is made outside the sound waves(vibrations) travel down the external auditory canal and
strike the ear drum. The ear drum vibrates and the vibrations are passed to the 3 tiny bones in the
middle ear. The ossicles amplify the sound and send the vibrations into the fluid in the cochlea. Once the
vibrations reach the inner ear they are converted into electrical impulses. The auditory nerve sends the
impulses to the brain. The brain then translates these electrical impulses as sound.
The ear is an organ of hearing and balance. Its functions are made possible by various parts in it.
Parts of the ear
The ear is divided into mainly three parts: outer ear, middle ear and inner ear. The outer ear consists of:
pinna, external auditory canal and tympanic membrane. The middle ear consists of; ossicles and
Eustachian tube while the inner ear consists of; cochlea, vestibule and semicircular canals.
The outer ear
Pinna: this is the visible part of the ear. Its purpose is to catch sound waves, amplify them and funnel
them down to the eardrum.
External auditory canal: this is the tube that connects the outer ear to the middle ear.
Tympanic membrane(eardrum): the tympanic membrane is a very thin structure that divides the outer
ear from the middle ear.
The middle ear
Ossicles: consists three small bones that are connected and transmit the sound waves to the inner ear.
The bones are; malleus, incus and stapes. The oval window membrane is one of the two membranes
that separate the middle ear space from the inner ear. The other is the round window membrane.
Eustachian tube: this is a canal that links the middle ear with the back of the bone. It helps to equalize
the pressure in the middle ear which is necessary for proper transfer of sound waves.
Inner ear
Cochlea: consists of hearing nerves. Has sensory hair cells which convert the mechanical energy from
the vibrations of the basilar membranes into electrical impulses.
Vestibules: this contains receptors for balance
Semicircular canals: contains receptors for balance
How exactly does hearing occur?
When a sound is made outside the sound waves(vibrations) travel down the external auditory canal and
strike the ear drum. The ear drum vibrates and the vibrations are passed to the 3 tiny bones in the
middle ear. The ossicles amplify the sound and send the vibrations into the fluid in the cochlea. Once the
vibrations reach the inner ear they are converted into electrical impulses. The auditory nerve sends the
impulses to the brain. The brain then translates these electrical impulses as sound.
