Bony labyrinth (English)

The bony labyrinth is located within the petrous part of the temporal bone. It consists of three continuous parts: vestibule, cochlea and semicircular canals.The vestibule is a central bony cavity which communicates with the middle ear through the vestibular window on its lateral wall. Posterosuperiorly, the vestibule is continued by the three semicircular bony canals, each placed in a specific anatomical plane. The anterior canal lies in the sagittal plane, the posterior is in the lateral plane, while the lateral canal lies in the transverse plane. The canals arise from the vestibule via bony ampullae (anterior, posterior, lateral). They curve through their respective planes, diving back into the bony vestibule. The lateral canal does so directly, while the anterior and posterior canals merge forming the common bony limb which then joins the vestibule.The cochlea is a snail-like structure that spirals from the anterior part of the vestibule. The cochlea is essentially a bony canal that spirals around its axis two and a half times. The central portion of the cochlea, i.e. the axis, around which it spirals is called the modiolus. Along the entire length of the cochlea is a thin bony lamina which divides the cochlea into two parts: scala vestibuli and scala tympani. These sub-canals are entirely separate except at the apex of the cochlea, where they communicate through a narrow slit called the helicotrema.The whole bony labyrinth is filled with perilymph.