Anteriorly it extends to the apex of the petrous temporal. It is separated from the posterior fossa by the clivus and the petrous crest. The lateral approach is then used to reach the medial cavernous sinus and petrous apex. Terminologia Anatomica in 1998 subdivided the artery into four parts&colon; "cervical", "petrous", "cavernous", and "cerebral". Similar symptoms can also occur secondary to petrous fractures or to nasopharyngeal tumours. In 2015 it was found, surprisingly, that the petrous bone has remarkably well-preserved DNA. Petrous comes from the Latin word "petrosus", meaning "stone-like, hard".