Endoscopic endonasal approach to the middle clivus. The meningeal dural layer of the left side of the clivus has been removed to expose the intradural structures. The basilar artery runs in the midline and gives off the anterior-inferior cerebellar artery (AICA) and several perforating branches to the pons. The intradural segment of the abducens nerve can now be identified running superiorly from its origin at the ponto-medullary sulcus. The abducens nerve pierces the meningeal dura just behind the medial edge of the paraclival ICA and continues ascending interdurally towards Dorello’s canal to enter the cavernous sinus. (Image courtesy of JC Fernandez-Miranda)