Left lateral view of inner ear following petrosectomy. The tympanic membrane has been removed as have the ossicular chain. Inferior to the lateral semicircular canal is the tympanic segment of the facial nerve  before continuing as the mastoid segment within the facial canal. The chorda tympani is shown passing through the tympanic cavity in a posterior to anterior direction. Immediately below the facial canal along the medial wall of the tympanic cavity is the oval window. Posterior to it on the posterior wall is the pyramidal eminence, a hollow conical projection of bone containing the stapedius muscle. Its tendon emerges through an opening at its apex and attaches to the neck of the stapes. (Image courtesy of AL Rhoton, Jr.)