Fig. 2

Supratubal recess (STR) measurements. a Axial CT through the left STR, showing measurements of length (STR-L) and width (STR-W) of STR. STR-L: the deepest anterior to posterior diameter (arrowhead) parallel to incudomalleal axis (red arrow). STR-W: distance between medial and lateral borders of cog (curved yellow arrow). b, c Measurement of STR height (STR-H) in coronal CT, from tegmen tympani to the cochleariform process (red arrows), adjacent to the tensor tympani muscle. The cochleariform process separates the tensor tympani (hypoattenuating focus superolateral to the cochleariform process) from the bony Eustachian tube (inferomedially)