Abstract
The endoscopic endonasal pathway allows access to the entire sphenoid, clivus, and craniovertebral junction; this approach has been used for the management of either extradural or intradural lesions from the retrosellar area down to the craniovertebral one. Accordingly, the posterior skull base can be divided into three levels that are cranial (from the posterior interclinoid line to the floor of the sella turcica), middle (from the floor of the sella turcica to the line connecting the hypoglossal canals), and caudal (at level of the craniovertebral junction). This chapter will describe the imaging features of the posterior fossa anatomy and will focus on the endoscopic endonasal approach technique. Finally, a surgical case concerning a large clival chordoma extending down to the craniovertebral junction will be provided.