Posterior superior view of posterior fossa. Multiple cranial nerves and intracranial venous sinuses can be observed in this perspective. The abducens nerve is shown piercing the dura along the clivus and ascending through Dorello's canal to enter the cavernous sinus. Facial and vestibulocochlear nerves converge on the internal auditory canal on the posteromedial wall of the petrous bone, while glossopharyngeal, vagus, and spinal accessory nerves converge on the jugular foramen. Jugular tubercles, small bony prominences arising from the inferolateral margins of the clivus, project over the hypoglossal canals toward which the hypoglossal nerves can be seen converging. Within the dural attachment to the superior border of the petrous bone is the superior petrosal sinus draining the cavernous sinus to the transverse sinus at the petrooccipital angle. Here, the transverse sinus continues as the sigmoid sinus toward the jugular foramen. The posterior arch of the atlas has been removed to show the odontoid process (dens) projecting superiorly from the body of the axis. Wrapping around the lateral masses of the atlas are the vertebral arteries. (Image courtesy of AL Rhoton, Jr.)