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Dictionary of Occupational and Environmental Safety and Health - Part 2

Một cấu trúc bên trong và bên ngoài để các bên đầu bao gồm ba khía cạnh chính (tai ngoài, tai giữa và tai trong), được sử dụng để nghe và cân bằng. Các tai ngoài bao gồm vành tai, Pinna, và meatus âm thanh bên ngoài. Vành tai thu thập các sóng âm thanh và chỉ đạo họ meatus âm thanh bên ngoài mà thực hiện các màng nhi (khoang tai giữa). Màng tympanic (màng nhĩ) phân tách các tai ngoài từ tai giữa. Trong tai giữa ba xương nhỏ: nhi chùy (gọi tắt là "búa" vì hình dạng. | Vincoli Jeffrey W. E-H Lewis Dictionary of Occupational and Environmental Safety and Health Edited by Jeffrey W. Vincoli Boca Raton CRC Press LLC 2000 E ear A structure within and external to the side of the head consisting of three major aspects external ear middle ear and inner ear which is used for hearing and equilibrium. The outer ear consists of the auricle or pinna and the external acoustic meatus. The auricle collects sound waves and directs them to the external acoustic meatus which conducts them to the tympanum the cavity of the middle ear . The tympanic membrane eardrum separates the outer ear from the middle ear. In the middle ear are the three ossicles the malleus referred to as the hammer because of its shape the incus or anvil and the stapes or stirrup . These three small bones form a chain across the middle ear from the tympanum to the oval window in the membrane separating the middle ear from the inner ear. The middle ear is connected to the nasopharynx by the Eustachian tube through which the air pressure on the inner side of the eardrum is equalized with the air pressure on its outside surface. The middle ear is also connected with the cells in the mastoid bone just behind the outer ear. Two muscles attached to the ossicles contract when loud noises strike the tympanic membrane limiting its vibration and thus protecting it and the inner ear from damage. In the inner ear or labyrinth is the cochlea containing the nerves that transmit sound to the brain. The inner ear also contains the semicircular canals which are essential to the sense of balance. When sound strikes the ear it causes the tympanic membrane to vibrate. The ossicles function as levers amplifying the motion of the tympanic membrane and passing the vibrations on to the cochlea. From there the vestibulocochlear eighth cranial nerve transmits the vibrations translated into nerve impulses to the auditory center in the brain. See also external ear middle ear and inner ear. ear breadth The