Skull

About the Skull

The skull is the bony structure of the head and is made up of 22 bones, not counting the small bones of the middle ear. It has two main parts: the cranium, or neurocranium, formed by eight bones including the frontal, parietal, temporal, occipital, sphenoid, and ethmoid bones, which encloses and protects the brain, and the facial skeleton, formed by fourteen bones including the maxillae, zygomatic bones, nasal bones, and the mandible, the only freely movable bone of the skull. Most skull bones are joined by fibrous joints called sutures. In infants, the sutures are not yet fused and soft areas called fontanelles allow the skull to compress during birth and expand as the brain grows; premature fusion of sutures, craniosynostosis, can distort skull shape. The base of the skull contains many openings, called foramina, through which the spinal cord, cranial nerves, and blood vessels pass, the largest being the foramen magnum. Skull fractures can accompany serious head injuries.