Eustachian tube

one of two tubes, one on each side, that connect the middle EAR to the PHARYNX . The short (about 35-40 mm) tube is fine at the centre and wider at both ends and is lined with mucous membrane. It is normally closed but opens to equalize air pressure on either side of the eardrum. It was named after the 16th - century Italian anatomist Eustachio.