||The bony labyrinth
The bony labyrinth is composed of the vestibule, the three semi-circular canals and the cochlea. The vestibule, which is situated between the middle ear and the internal auditory canal, communicates with the semi-circular canals posteriorly and the cochlea anteriorly.
The vestibule communicates with the middle ear by means of two windows in its lateral wall, the oval window which is occupied by the stapes footplate, and the round window which is covered by the thin round window membrane.
Each of the three semi-circular canals (superior, lateral and posterior) forms two-thirds o a circle and has a small swelling (the ampulla) at one end.
The bony otic capsule of this right ear has been dissected.
The cochlea (C) is located anteriorly. All three semi-circular canals: the superior (S), the horizontal (H) and the posterior (P)-can be clearly seen. The oval window (0) from which the stapes footplate has been removed and the round window niche (R) are also clearly visible.