{Eustachian catheter}, a tubular instrument to be introduced
into the Eustachian tube so as to allow of inflation of
the middle ear through the nose or mouth.
{Eustrachian tube} (Anat.), a passage from the tympanum of
the ear to the pharynx. See {Ear}.
{Eustachian valve} (Anat.), a crescent-shaped fold of the
lining membrane of the heart at the entrance of the vena
cava inferior. It directs the blood towards the left
auricle in the fetus, but is rudimentary and functionless
in the adult.