View of the presigmoid region after petrosectomy. The internal jugular vein serves as a landmark from the jugular bulb to the common facial vein. The petrous bone has been removed to reveal cranial nerves III, IV and V. Significant branches of the mandibular nerve (V3) include the lingual nerve, the buccal nerve, the inferior alveolar nerve, the nerve to the medial pterygoid, and the auriculotemporal nerve. The spinal accessory nerve exits the skull through the jugular foramen and crosses the IJV to course posterolaterally over the levator scapulae muscle. The terminal branches of the external carotid artery, in ascending order, include the occipital artery, the posterior auricular artery, the superficial temporal artery, and the internal maxillary artery. The inferior alveolar artery, a branch of the maxillary artery, courses adjacent to the inferior alveolar nerve of V3. The vagus nerve runs within the carotid sheath, between the ICA and IJV. (Image courtesy of AL Rhoton, Jr.)