Section 300: The hook portion of the cochlea duct (cd) is visible on the medial wall of the middle ear space. The promontory (p) which bulges into the middle ear space marks the position of the hook. Only a small part of the vestibule (v) remains. The end of the foramen singulare (fs) is visible. The non-sensory portion of the posterior semicircular canal (psc) is still present. The endolymphatic sac (es) is located in the posterior cranial fossa. VIIf - Mastoid segment of facial nerve.