eu·sta·chian tube or Eu·sta·chian tube 
(y-stāshən, -shē-ən, -kē-ən)
(y-stāshən, -shē-ən, -kē-ən)n.
Anatomy
Anatomy
A slender tube that connects the tympanic cavity with the nasal part of the pharynx and serves to equalize air pressure on either side of the eardrum.
[After Bartolomeo Eustachio.]