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Unformatted text preview: Hearing The organ of hearing, the ear, consists of three major regions, shown in Figure 1. The outer (external) ear consists of the auricle (pinna), a flap of elastic cartilage that protrudes from the head, and the external auditory canal (meatus), a tube that enters the temporal bone. The canal is lined with ceruminous glands that secrete cerumen (earwax), a sticky substance that traps dirt and other foreign objects. The eardrum (tympanic membrane), at the internal end of the external auditory canal, vibrates in response to incident sound waves. The middle ear (tympanic cavity) is an air-filled cavity within the temporal bone. It contains three small bones, the auditory ossicles. These bones, called the malleus, incus, and stapes, act as a lever system that amplifies and transfers vibrations of the eardrum to the inner ear. The malleus at lever system that amplifies and transfers vibrations of the eardrum to the inner ear....
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- Spring '10