has part has part characteristic of has modifier Abnormal facial shape Flat face A useful guide is to imagine that a line connecting the glabella to the anterior most part of the mandible touches the top of the philtrum where it meets the base of the columella. The glabella is the most prominent point on the frontal bone above the root of the nose. If the superior philtrum is anterior to this line the face is convex, if the superior philtrum is posterior to this line the face is concave. flat abnormal face