Figure 2: Simplified schematic illustration of the skull viewed from the front.
The line labeling “Z” defines a plane parallel to the horizontal. The measuring points AgR and AgL are usually not parallel to the Z plane: the angle of both distances defines gamma. In FPNF patients, Ag of the affected side frequently is more cranially situated than on the non-affected side. For didactic reasons, the drawing reproduces a significant maxillomandibular dysplasia, which causes a higher antegonion notch on the right side with a deformed mandibular ramus. The skeletal as well as the dentoalveolar conditions of the NF1 patients, namely the FPNF patients with tumors of the mandibular trigeminal branch, may deviate from the simplified proportions presented here.