What overlies the lateral wall of the mastoid antrum?

BOUNDARIES: SUPERIORLY-Tegmen tympani and beyond it the temporal lobe of the cerebrum INFERIORLY-Mastoid process containing the mastoid air cells ANTERIORLY-It communicates with the epitympanic recess through the aditus. The aditus is related medially to the ampullae of the superior and lateral semicircular canals. and posterosuperiorly to the facial canal POSTERIORLY-It is separated by a thin plate of bone from the sigmoid sinus. Beyond the sinus, there is the cerebellum MEDIALLY-Petrous temporal bone LATERALLY-It is bounded by pa of the squamous temporal bone. This pa corresponds to the suprameatal triangle seen on the surface of the bone. Ref:BDC VOLUME 3,sixth edition pg 281