The term CRANIAL CAVITY is a five-letter word, SINUS. The cranial cavity is the space within the skull that houses the brain and other structures of the head. It is also known as the intracranial cavity or the intracranial space. The cranial cavity is divided into two parts: the anterior cranial fossa and the posterior cranial fossa. The sinuses are air-filled cavities located within the cranial cavity, which help to reduce the weight of the skull and provide resonance for the voice.