Human skull. Coloured X-ray of a sagittal section through a human skull. The skull has been sliced in half down the centre, revealing details of the internal structures. These include the delicate bones and spaces of the paranasal sinuses (around the nose and eyes, centre left). The fused bones of the cranium encase and protect the brain. The nasal, cheek and upper jaw bones are fused to the cranium to form the facial skeleton (left). The lower jaw bone (mandible, lower left), is attached at flexible joints, allowing it to move. The upper and lower jaw bones contain 32 permanent teeth (lower left). The eye sockets (one at far left) house the eyes.