The outer ear is the external portion of the ear and includes the fleshy visible pinna (also called the auricle), the ear canal, and the outer layer of the eardrum (also called the tympanic membrane). The inner ear contains the otolith organs-the utricle and saccule-and the semicircular canals belonging to the vestibular system, as well as the cochlea of the auditory system. The middle ear contains the three small bones-the ossicles-involved in the transmission of sound, and is connected to the throat at the nasopharynx, via the pharyngeal opening of the Eustachian tube. The ear canal of the outer ear is separated from the air-filled tympanic cavity of the middle ear by the eardrum. The human ear consists of three parts-the outer ear, middle ear and inner ear. The ear has been adorned by earrings and other jewelry in numerous cultures for thousands of years, and has been subjected to surgical and cosmetic alterations. Diseases of the ear may lead to hearing loss, tinnitus and balance disorders such as vertigo, although many of these conditions may also be affected by damage to the brain or neural pathways leading from the ear. The ear may be affected by disease, including infection and traumatic damage. The ear develops from the first pharyngeal pouch and six small swellings that develop in the early embryo called otic placodes, which are derived from ectoderm. The ears of vertebrates are placed somewhat symmetrically on either side of the head, an arrangement that aids sound localization. The ear is a self cleaning organ through its relationship with earwax and the ear canals. The inner ear sits in the bony labyrinth, and contains structures which are key to several senses: the semicircular canals, which enable balance and eye tracking when moving the utricle and saccule, which enable balance when stationary and the cochlea, which enables hearing. The middle ear includes the tympanic cavity and the three ossicles. Since the outer ear is the only visible portion of the ear in most animals, the word "ear" often refers to the external part alone. The outer ear consists of the pinna and the ear canal. In mammals the ear is usually described as having three parts: the outer ear, the middle ear and the inner ear. How sounds make their way from the source to the human brainĪn ear is the organ that enables hearing and (in mammals) body balance using the vestibular system.
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