Eustachian tube

The Eustachian tube /juːˌsteɪ.ʃənˈtjuːb/, also known as the auditory tube or pharyngotympanic tube, is a tube that links the nasopharynx to the middle ear. It is a part of the middle ear. In adult humans the Eustachian tube is approximately 35 mm (1.4 in) long. It is named after the sixteenth-century anatomist Bartolomeo Eustachi.

Structure
Upper respiratory system, showing entrance to audotory tube near middle.

The Eustachian tube extends from the anterior wall of the middle ear to the lateral wall of the nasopharynx, approximately at the level of the inferior nasal concha. It consists of a bony part and a cartilaginous part

A portion of the tube (1/3) proximal to the middle ear is made of bone; this bony part is about 12 mm in length. It begins in the carotid wall of the tympanic cavity, below the septum canalis musculotubarii, and, gradually narrowing, ends at the angle of junction of the squama and the petrous portion of the temporal bone, its extremity presenting a jagged margin which serves for the attachment of the cartilaginous portion of the rest of the tube,[3] and this raises a tubal elevation, the torus tubarius, in the nasopharynx where it opens.

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