Figure 1. 3-D reference points of the craniofacial structures and zygoma, cranium, and temporal fossa widths (A) Orbit (left, right) (or_l, or_r), the most inferior point of the orbit bone ridge; porion (left, right) (po_l, po_r), the most latero-superior point of the external auditory meatus; basion (bs), the coronal midpoint on the anterior margin of the foramen magnum; zygoma anterior (zg_a), the most anterior point of the origin of the masseter muscle; zygoma posterior (zg_p), the buccolingual midpoint of the deepest point on the antero-inferior region of the zygomatic arch; zygoma exterior (zg_e), the most exterior point of the upper margin of the zygomatic arch; cranium exterior (cr_e), the deepest point of the cranium on the temporal fossa; apex of the condylar head (cd), the most superior point of the condylar head; mandible anterior (mn_a), the buccolingual midpoint of the most anterior point of the insertion of the masseter muscle on the mandible; mandible posterior (mn_p), the buccolingual midpoint of the most posterior point of the insertion of the masseter muscle on the mandible; gonion (gn), the buccolingual midpoint of the most prominent point of the mandibular angle; mandibular ramus notch (mnn), the deepest point of the mandibular notch; and mandibular ramus center (mnc), on axial slices the buccolingual midpoint of the given line through the open site of the mandibular foramen, which is perpendicular to the anteroposterior axis of the ramus. (B) Zygoma width (ZgW), the distance between bilateral zg_e points projected to the intersection between the FHP and the FP; cranium width (CrW), the distance between bilateral cr_e points projected to the intersection between the FHP and the FP; and temporal fossa width (TFW), the distance between the zg_e and the cr_e points projected to the intersection between the FHP and the FP.