Left posterolateral view of the bony labyrinth and middle ear cavity following mastoidectomy and removal of the tympanic membrane. The opening of the Eustachian tube can be seen at the anterior wall of the tympanic cavity. The mastoid segment of the facial nerve is shown giving rise to the chorda tympani that courses anteriorly between the handle of the malleus and long crus of the incus.  The sigmoid sinus (not shown), which courses posterior to the labyrinth, continues into the jugular bulb located inferior to the labyrinth. (Image courtesy of AL Rhoton, Jr.)