Child's skull. Coloured X-ray of a side-ways view of a child's skull. The cranium (centre) encloses and protects the brain. A pointer is identifying the maxilla (upper jaw), behind the nasal cavity. Above the nasal cavity is an eye socket (round). To the left of the nasal cavity is one of the paranasal cavities (air-filled space). The sinuses decrease the weight of the front of the skull, aid in warming and humidifying inhaled air, and increase the resonance of the voice. At bottom right is the lower jaw (mandible) with the teeth embedded in it.