The skull is the bony structure that encases the brain and protects it from injury. It is located anterior to the spinal column and is composed of 22 bones that form two regions: the cranial and facial regions. The cranial portion directly houses the brain, while the facial portion includes the rest of the bones of the skull. The skull also supports tendinous muscle attachments and allows neurovascular passage between intracranial and extracranial anatomy. The skull is embryologically derived from mesoderm and neural crest and will fuse, harden, and mold from gestation through adulthood. The skull is one of the first structures to develop in an embryo and continues to grow and change throughout gestation and infancy. The skull serves two major purposes: it surrounds and protects the brain, brainstem, and eyes, and it provides the structure for the muscles, blood vessels, and connective tissue that make up the face and scalp. The skull is supported by the highest vertebra, called the atlas, permitting nodding motion. The skull is made up of a number of fused flat bones, and contains many foramina, fossae, processes, and several cavities or sinuses.