Fig. 2.

Pictures showing anatomical landmarks (A) and the reference plane (B). Sellion is set at the most concave point in the soft tissue on the naso-frontal angle between the forehead slope and the proximal nasal bridge. Tragion is set at the upper margin of the tragus. After setting these landmarks the origin is set at the midpoint between the right and left tragia. Then the Y-axis is defined as a line through the sellion and the origin. The X-axis was defined as the line perpendicular to the Y-axis that crosses the origin. Level 0 is the reference cross-sectional plane including sellion and both tragia. The portion of the cranium superior to the reference plane was divided into 9 equally spaced cross-sectional planes, each parallel to the reference plane, where the level 10 is the plane through vertex. Anthropometric measurements on level 3 and 5 planes were used in this study.