Fig. 42-22. The growth of the skull. A and B, Neonatal skull. C and D, Adult skull. The scale used for the adult is half that of the neonatal skull. The horizontal lines indicate the orbitomeatal plane. In the infant's skull, although the vault appears large, the facial region (chiefly below the horizontal line) is relatively small. The jaws, nasal cavities and paranasal sinuses are all small, and the orbits and teeth are close together. In the adult, however, the horizontal line approximately bisects the vertical height of the skull. Note the fontanelles in A and B. (Based chiefly on the work of J. C. Brash.) Click for high resolution image.