part of part of cranium posterior cranial fossa NCIT:C33361 MESH:D003388 FMA:54368 CALOHA:TS-2354 posterior fossa GAID:85 Wikipedia:Posterior_cranial_fossa UBERON:0008788 The infratentorial compartment that contains the CEREBELLUM and BRAIN STEM. It is formed by the posterior third of the superior surface of the body of the sphenoid (SPHENOID BONE), by the occipital, the petrous, and mastoid portions of the TEMPORAL BONE, and the posterior inferior angle of the PARIETAL BONE. cranial fossa