The human ear consists of three sections: the outer ear, the middle ear, and the inner ear. The outer ear includes the auricle (pinna), the visible part of the ear that is attached to the side of the head, and the waxy, dirt-trapping auditory canal. The framework of the auricle consists of a single piece of yellow fibrocartilage with a complicated relief on the anterior, concave side and a fairly smooth configuration on the posterior, convex side. The outer ear consists of an ear flap and an approximately 2-cm long ear canal. The tympanic membrane (eardrum) separates the external ear from the middle ear, an air-filled cavity. The eardrum is a very durable and tightly stretched membrane which vibrates as the incoming pressure waves reach it. Bridging this cavity are three small bones—the malleus (hammer), the incus (anvil), and the stapes (stirrup). The cochlea and semicircular canals make up the inner ear.
see http://encarta.msn.com/media_701765656_761563171_-1_1/Ear_and_Hearing.html
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