Ear

The ear is a sense organ that detects sound. It consists of three parts: the outer ear, the middle ear, and the inner ear. The outer ear includes the skin-covered flap of cartilage called the auricle, or pinna, and the short external auditory canal leading to the eardrum. The middle ear contains three tiny bones—the malleus (hammer), incus (anvil), and stapes (stirrup)—that transmit sound from the eardrum to the inner ear. The air-filled cavity of the middle ear is connected to the throat by a passageway called the Eustachian tube, which helps equalize pressure on both sides of the eardrum. The innermost part of the ear is filled with fluid and lined with hair cells that vibrate when stimulated by sound waves passing through this fluid. These vibrations are transmitted by nerve fibers to regions in temporal lobe of brain where they are interpreted as sounds.