Figure 4. Transverse multi-detector row CT scan of a normal left temporal bone. A normal incudomallear articulation (1) is shown. The saccular nerve, a branch of the inferior division of the vestibular nerve runs in its own canal (2) from the fundus of the internal auditory canal to the vestibule. The canal of the accessory nerve of the posterior ampullary nerve (3) and canal of the posterior ampullary nerve (4) emerge from the posterior wall of the internal auditory canal. Both run separately to the posterior ampulla (5).