The Skull Quiz

See The Calvaria. Option B is correct. The calvaria is the roof of the neurocranium (the part of the skull that encases the brain). It is made of four bones, the frontal bone, the occipital bone and the two parietal bones, and these are joined to one another by sutures, which are fibrous joints that are immobile in adults. The three main sutures are the coronal suture, which joins the frontal bone with the two parietal bones; the sagittal suture, which joins the two parietal bones in the midline; and the lambdoid suture, which joins the occipital bone to the two parietal bones. In infants the sutures are wide, which leaves membranous gaps called fontanelles and permits the skull to enlarge as the brain grows. A plain memory aid: the sagittal suture runs front to back along the middle of the head like an arrow (sagitta is Latin for arrow), between the two parietal bones.

• Sagittal suture: joins the two parietal bones in the midline.
• Direction: it runs front to back along the middle of the head.
• Other sutures: the coronal suture lies between the frontal and parietal bones, and the lambdoid suture between the occipital and parietal bones.