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