<prompt> Which of the following structures is not at immediate risk of erosion by cholesteatoma ?Long process of incusFallopian canal containing facial nerveHorizontal lateral semicircular canalBase plate of stapes  <response>: Ans. is d i.e., Base plate of stapes Cholesteatoma has the propey to destroy the bone by viue of the enzymes released by it. Structures immediately at the risk of erosion are : - Long process of incus. Fallopian canal containing facial nerve. Horizontal lateral semicircular canal 