Internal ear

The internal ear is one of the parts of the Oreille, which contains not only the body of hearing, the cochlea or snail ( cochlea ), but also the hall, body of balance, person in charge of the perception of the angular position of the head and its acceleration. The movements of the clamp are transmitted to the cochlea via the oval window and the hall.

The cochlea is a hollow body filled with a liquid called endolymphe ( endolympha ). It is papered of ciliées cells - capped sensory cells of filamentous structures, the stéréocils ( stereocilia ), grouped in a free tuft ciliaire to vibrate. These cells are laid out along a membrane (the membrane basilaire ) which comes partitionner the cochlea in two rooms. The whole of the ciliées cells and the membranes which are assistant for them constitute the body of Corti .

The ciliées membrane basilaire and cells which it door are put moving by the vibrations transmitted through the median ear. Along the cochlea, each cell answers a certain frequency preferentially, to make it possible the brain to differentiate the height from the sounds. Thus, the ciliées cells closest to the base of the cochlea (oval window, with more close to the median ear) answer the acute ones preferentially. Those located in its apex (last tower of the cochlea) answer the low frequencies.

In fact the ciliées cells make mecanoelectric transduction: they transform a movement of their tuft ciliaire into nervous Signal by the auditive Nerf, which will be interpreted by the brain like a sound of the tonal Height corresponding to the excited cell.

The vestibular apparatus constitutes of three semicircular channels , orthogonally arranged on the three planes. They are filled of same the endolymphe as the cochlea. When the ear is subjected to a movement, the inertia of this liquid makes this movement detectable by ciliées cells, completely similar to those of the cochlea. The provision of the three channels in three orthogonal plans makes it possible to detect the angular position of the head in all the possible directions.

The internal ear can be affected by the catch of drugs Ototoxique S.

The sound can also damage the internal ear. During an exposure to a sound of high intensity of the ciliées cells are destroyed and cannot be replaced. The effects are cumulative and can bring to a progressive loss of the hearing which starts starting from the high frequencies, even to deafness. Sounds of extraordinary intensity, as the explosions but also the amplified music can damage the internal ear suddenly, by causing a fall of hearing, the Hyperacousie and the Acouphènes.

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