any structural anomaly of the passageway within the petrous temporal bone that transmits the internal carotid artery and sympathetic plexus; its inferior opening is the carotid foramen situated anteriorly to the jugular fossa and medially to the tympanic plate; the carotid canal is initially directed superiorly, then turns anteromedially to reach up to the petrous apex, runs within the petrous bone, and opens into the middle cranial fossa superior to the foramen lacerum