Eustachian Tube
eustachian tube
"A tubular structure that runs from the middle ear to the nasopharynx and is approximately 3-4 cm length. Its lumen is roughly triangular and has average diameter of 2-3 mm. The lumen is lined by ciliated pseudostratified, columnar epithelium, which sweeps material from the middle ear to the nasopharynx. It is functionally collapsed at rest, with slight negative pressure present in the middle ear, and opens during swallowing, sneezing, and yawning.  It serves to ventilate pressure differences between the middle ear and nasopharynx. This tube also allows middle ear secretions to drain into the nasopharynx."