Which of the following structures is not at immediate risk of erosion by cholesteatoma
An attic cholesteatoma may extend backwards into the aditus, antrum and mastoid; downwards into the mesotympanum; medially, it may surround the incus and/or head of malleus. Cholesteatoma has the propey to destroy bone. It may cause destruction of ear ossicles, erosion of bony labyrinth, canal of facial nerve, sinus plate or tegmen tympani and thus cause several complications. Ref: Dhingra 7e pg 74.
Long process of incus
Fallopian canal containing facial nerve
Horizontal/ lateral semicircular canal
Basal plate of stapes
Ear