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THE HUMAN EAR

The ear is a complex sense organ whose functions are to perceive sound and
maintains balance in the body
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The outer ear
Consists of the pinna and external auditory meatus
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It
mainly collects and concentrates sound waves into the auditory meatus
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The tube is lined with hairs which trap solid
particles that may enter the ear
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It also
maintains flexibility of the eardrum
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The tympanic membrane is a thin rough
membrane that covers the external opening of the middle ear
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When it is
hit by sound waves from outside, it vibrates and transforms sound waves into
vibrations
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The ear ossicles are
three bones namely malleus, incus and stapes which are suspended in position by
muscles
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The three ossicles form a layer of levers
which amplifies and transmits the vibrations from tympanic membrane to the oval
window
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Its
function is to equalize air pressure between the middle ear and the outer ear to
prevent distortion of the eardrum
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It
consists of a series of chambers and canals embedded in the bone of the skull
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The cavities in the inner ear
are filled with fluids called perilymph and endolymph
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In the

vestibule and semi-circular canals, the displacements of the fluids lead to
restoration of the body balance
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THE HEARING PROCESS

The cochlea is the structure responsible for hearing
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The canals are
filled with endolymph and perilymph
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First, the pinna concentrates sound waves into auditory meatus
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The vibrations are transmitted to the ear
ossicles in the middle ear
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The stapes
passes the vibrations to the oval window from where the vibrations are transmitted
to the perilymph of the cochlea
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In the cochlea the vibrations stimulate the
sensory hairs to generate nerve impulses which are transmitted to the brain via the
external auditory nerve for interpretation
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Vibrations in the fluid of the inner ear are dissipated back into the middle ear
through the round window
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The direction
of sound is detected accurately as a result of both ears functioning together
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The
intensity of the impulses by the auditory nerve will be of equal strength
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MAINTENANCE OF BODY BALANCE AND POSTURE
Balance is brought about by the semi-circular canals and the vestibule
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Are three tubular cavities containing endolymph
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Two of the canals lie vertically
and at right angles to one another while the third is horizontal
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They maintain the
body balance and posture in relation to movement of the head
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They maintain
body balance and posture in relation to gravity
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There are two categories; permanent deafness, partial deafness
Permanent deafness is due to damage of either the cochlea or the auditory nerve
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