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Different Parts of Ear

Outer ear

It consists of Pinna, ear canal and ear drum. Pinna (also called auricle): It is outer most (and visible) portion of ear. Its external parts are wide while inner portion is narrow. Because of its shape it act as a funnel (collects the sound and directs it through ear canal to ear drum).

Ear canal (auditory canal): It contains sebaceous glands which secrete ear wax (cerumen) for lubrication of ear.

Ear drum (tympanic membrane): It is thin membrane located at the end of outer ear. It carries the sound towards middle ear.

Middle ear

It consists of three ear bones or ossicles (malleus, incus and stapes). These ossicles transmit sound to the inner ear.

Malleus (also called hammer):
It is hammer like ossicle. Its one end is attached to ear drum while other is connected with incus.

Incus (anvil):
It is anvil shaped bone, attached with malleus and stapes.

Stapes:
stirrup shaped bone attached to incus and oval window or vestibular window (membrane covered opening between middle ear and inner ear).

Inner ear

It contains cochlea, vestibule and semicircular canals.

Cochlea:
It is coiled portion and auditory portion of inner ear.

Semi-circular canal:
Three fluid filled canals horizontal semi-circular canal, posterior semi-circular canal and anterior semi-circular canal are called semi-circular canals.
The fluid inside these canals is called endolymph. The dilation at one end of canal is called ampulla. Ampulla contains Cupula and hair cells.
Semi-circular canals are responsible for body balance and detect direction of rotation of head.

Vestibule:
It is located between the semi-circular canals and cochlea. Its anterior and inferior part has several minute holes for the passage of filaments of acoustic nerve (auditory nerve) to saccule. Saccule detects the motion of head when it moves vertically. At the upper and back of vestibule a structure called utricle detects the degree of tilt movement of head.

Tags : science
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