This is the plate-like, partial ring of bone that forms the anterior, inferior, and inferoposterior walls of the external acoustic meatus.

There is no clear evidence of the mention of the tympanic membrane or eardrum in ancient anatomical history. It was first described in the literature in 1255 by Albertus Magnus. He named it the tympanum auris because of its resemblance to a drum. It comes from the Greek word tympanon meaning drum. Annulus is the Latin diminutive of annus meaning a little ring.