has part has part characteristic of part of has modifier Abnormal posterior cranial fossa morphology The floor of the cranial cavity is divided into three distinct depressions called the anterior, middle, and posterior cranial fossa. The posterior cranial fossa, the most posterior and deep of the three cranial fossae, accommodates the brainstem and cerebellum. Abnormalities of the posterier cranial fossa can be demonstrated by cerebral magnetic resonance imaging or computer tomography. Abnormal skull base morphology morphology abnormal posterior cranial fossa