The prosthion is the lowermost point on the maxilla, between the two front incisors. The inion is the place on the back of the skull that is the grates t distance away from the front of the skull.

Indices calculated are the index of supraorbital height, index of nuchal area height and the index of condylar conditions. The index of supraorbital height is the relationship between the distance of the Frankfort plane to the highest point of the skull and the distance of the top of the eye orbit to the top of the skull. a high number indicates a high forehead or a tall head while a low number indicates a slanted skull. The index of nuchal area is the relationship between the distance of the Frankfort plane to where the inion lies on the back of the skull and the distance of the Frankfort to the highest point on the skull. a high number indicates a short nuchal area while a low number indicates a tall nuchal area.

The index of the condylar position is the relationship between the porion and the back of the skull and porion and the front of the skull. a high number indicates the foramen magnum is at the center of the skull while a low number indicates the foramen is closer to the back of the skull.

The marked locations were then connected with fine lines using a sharp pencil. A line was drawn to intersect the porion and the lowest point on the lower margin of the eye orbit. A line was also drawn to from the inion, perpendicular to the line drawn above (Frankfort Plane) and the point of intersection labeled as Y. Another line was drawn from the occipital condyles perpendicular to the Frankfurt Plane and the point of intersection labeled X. Another line was drawn from the prosthion perpendicular to the Frankfort plane and the point of intersection labeled Z. Another line was drawn from the Frankfort plane to the highest point of the upper margin of the eye and the point labeled V and U.

The lengths of the line were then measured,