The cranium, or skull, protects the fragile brain from damage, according to the BBC. In humans, the cranium is composed of eight different bones that grow together. These different bones attach at areas called sutures.
The BBC explains that the human skull is almost full-grown at the time of birth; however, the various bones haven't yet fused together, which allows the skull to warp and stretch in order to fit through the birth canal. Over approximately 24 months, the sutures become rigid.
The BBC explains that the cranium is not the only structure that protects the brain. In addition to the bones that form the skull, 14 facial bones attach to the front of the skull. The facial bones help to hold the nose and eyes in place and provide an attachment point for the mandible, or lower jawbone. The mandible is the only bone in the entire skull that moves freely. The Mayo Clinic notes that the jawbone connects to the skull at a place called the temporomandibular joint.