Figure 1: (a) Normal sagittal oblique 3D CISS MR Image perpendicular to the fundus of the internal auditory canal. The anterior (A), posterior (P), superior (S), and inferior (I) aspects of the canals are labeled for ease of orientation. The facial (white arrow), superior vestibular (black arrow), inferior vestibular (black arrowhead), and the cochlear nerves (white arrowhead) are depicted. (b) Right Ear agenesis of the cochlear nerve. (c) Left Ear agenesis of the cochlear nerve. Note on the sagittal oblique section the facial nerve in the anterosuperior quadrant (white arrow). Only one vestibular nerve is seen in the posterior quadrant (black arrowhead), showing incomplete separation of the superior and inferior vestibular nerves. The cochlear nerve is absent in the anterior inferior quadrant (white arrowhead).