All are true about Mastoid antrum except

(B) It does not communicate with middle ear# Mastoid Antrum:> Is a large, air-containing space in the upper part of mastoid and communicates with the attic through the aditus.> Its roof is formed by the tegmen antri and is a continuation of the tegmen tympani and separates it from the middle cranial fossa.> The lateral wall of antrum is formed by a plate of bone which is on an average 1.5 cm thick in the adult.> It is marked externally on the surface of mastoid by suprameatal (MacEwen's) triangle.