<prompt> Which of the following structures is not at immediate risk of erosion by cholesteatomaLong process of incusFallopian canal containing facial nerveHorizontal lateral semicircular canalBasal plate of stapes  <response>: An attic cholesteatoma may extend backwards into the aditus, antrum and mastoid; downwards into the mesotympanum; medially, it may surround the incus andor 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. 