NCIt definition : The portion of the skull that forms the floor on which the brain lies. The internal
surface of the cranial base has three large depressions that lie on different levels
known as the anterior, middle, and posterior cranial fossae.;
Alternative definition : CDISC: The portion of the skull that forms the floor on which the brain lies; the
internal surface of the cranial base has three large depressions that lie on different
levels known as the anterior, middle, and posterior cranial fossae.;