The BBC explains that the human cranium is composed of eight different bones. These bones are connected to each other via fixed joints, called sutures. In conjunction with the 14 facial bones, the cranium and face comprise the skull. Suture joints connect many of the facial bones together, but the mandible, or lower jawbone, is the skull’s only freely moving joint.
According to Wikipedia, the cranium is comprised of one ethmoid bone, one frontal bone, one occipital bone, two parietal bones, one sphenoid bone and two temporal bones. The frontal bone spans across most of the forehead, while the occipital bone forms the rear portion of the skull. The sphenoid and temporal bones form much of the skull’s sides, while the parietal bones form the sides and top of the skull.
The bones of the human cranium are not fused together at birth. As Seattle Children’s Hospital explains, newborns are better able to pass through the birth canal with non-rigid skulls. However, as babies grow and age, the bones begin to fuse. At 2 or 3 years of age, the bones in children's skulls begin to grow together. This growth continues until adulthood.
Seattle Children’s Hospital states that problems can occur during the fusion of the cranial bones. A condition called craniosynostosis involves the premature fusing of cranial bones. When this happens, a child’s skull cannot grow and develop normally.