Classification of the clival region; transcranial approaches. The upper clivus is formed by the dorsum sellae and posterior clinoids, and it is limited inferiorly by the petrous apex. An antero-lateral approach, such as fronto-temporal or its orbitozigomatic variant, is used to access the upper clivus. The middle clivus runs from the petrous apex to the anterior edge of the jugular foramen. It is typically accessed via anterior and/or posterior transpetrosal approaches. The inferior clivus includes the jugular foramen, jugular tubercle, condyles, and foramen magnum. It is commonly approached using transcondylar routes ot its variants. (Image courtesy of JC Fernandez-Miranda)