 Facial nerve anatomy. Coronal SSFP image shows the expected locations of the root exit point (RExP, white arrowhead), the attached segment (AS) along the ventral surface of the pons, and the root detachment point (RDP, black arrowhead). The proximal cisternal segment (PC) extends ∼3 mm from the root detachment point to the lateral margin of the white line. The distal cisternal portion (DC) of the facial nerve extends from the lateral margin of the white line to the porus acusticus, which is not shown.