The cranium is the upper bony structure of the skull, including everything except for the mandible, or jawbone. The cranium protects the brain and head, and supports facial structures such as the eyes and ears, holding them in the proper place to receive sensory information most efficiently.Animals that have a skull are collectively known as craniates. The cranium is not a single bone, but many.he human cranium consists of 21 bones and is subdivided into the neurocranium or brain case, which surrounds and protects the brain, and the splanchnocranium, which supports the structures of the face.