Eustachian tube(redirected from Eustacian)
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Eustachian tube(yo͞ostā`shən) [for Bartolomeo EustachiEustachi, Bartolomeo
, d. 1574, Italian anatomist. He lived in Rome from 1549 and taught at the Collegia della Sapienza (later the Univ. of Rome). He described many structures in the human body, including the Eustachian tube of the ear, the adrenal glands, the thoracic duct, the
..... Click the link for more information. ], a hollow structure of bone and cartilage extending from the middle earear,
organ of hearing and equilibrium. The human ear consists of outer, middle, and inner parts. The outer ear is the visible portion; it includes the skin-covered flap of cartilage known as the auricle, or pinna, and the opening (auditory canal) leading to the eardrum (tympanic
..... Click the link for more information. to the rear of the throat, or pharynx, technically known as the pharyngotympanic or auditory tube. By permitting air to leave or enter the middle ear, the tube equalizes air pressure on either side of the eardrum. The tube can become blocked, as by enlarged adenoids or the mucous secretions of a cold, so that external and internal pressure become imbalanced. Earache and diminution of hearing may result. The tube may also serve as a pathway to the ear for infections of the throat. A common ear disease known as otitis media, usually appearing in early childhood, is thought to be related to the Eustachian tube. The tube tends to be shorter and more horizontal among children, factors which facilitate the spread of infections from upper respiratory diseases to the middle ear, as well as the accumulation of fluids in the region.
auditory tube, in terrestrial vertebrates, the canal that unites the pharynx with the cavity of the middle ear; named for B. Eustachio, who first described it in 1563.
The eustachian tube serves to equalize the air pressure in the middle ear with that of the surrounding environment. It originates from the rudiment of the gill slit. In crocodiles it forms a complex system of anastomosing canals. It is absent in snakes because of the reduction of the middle ear.
In man, the eustachian tube is a tubular formation that unites the nasopharynx with the tympanic cavity of the middle ear. Air enters the tympanic cavity through the eustachian tube from the nasopharynx. When the eustachian tube is inflamed, the entry of air into the tympanic cavity often ceases or is limited, producing a sensation of noise and congestion in the ear; hearing is somewhat decreased.