Entrance to the mastoid antrum
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Template:Infobox Anatomy Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
The entrance to the antrum is a large irregular aperture, which leads backward from the epitympanic recess into a considerable air space, named the tympanic or mastoid antrum.
The antrum communicates behind and below with the mastoid air cells, which vary considerably in number, size, and form; the antrum and mastoid air cells are lined by mucous membrane, continuous with that lining the tympanic cavity.
On the medial wall of the entrance to the antrum is a rounded eminence, situated above and behind the prominence of the facial canal; it corresponds with the position of the ampullated ends of the superior and lateral semicircular canals.