Fig. 2. (A) Posteroanterior cephalometric landmarks. 1, external peripheral cranial bone surface; 2, mastoid process; 3, occipital condyle; 4, nasal septum: crista galli, floor of nose; 5, orbital outline: inferior surface of the orbital plate of the frontal bone; 6, oblique outline: innominate line; 7, superior surface of the petrous portion; 8, lateral surface of the frontosphenoid process of zygoma and zygomatic arch (ZA); 9, cross section of zygomatic arch; 10, infratemporal surface of maxilla; 11, mandible: body, rami, coronoid process, condyles; 12, dental unit. (B) Posteroanterior cephalometric landmarks. Om, orbital midpoint, the point of the line connecting the right and left lo (lateral orbitale) at the base of the cristagalli that the highest point on the extenstion of the nasal septum, the reference point of sagittal plan; mo, medial orbitale, the nearest point on the medial orbital margin in median plan; tns, tip of nasal spine; ans, anterior nasal spine, the center point at the base of the nose; iif, incision inferior frontale: the central point of the mandibular central incisors end; isf, incision superior frontale: the central point of the maxillary central incisors end; m, mandibular midpoint; lo, lateral orbitale, lateral orbital margin and innominate line that intersects; lzmf, lateral zygomatic frontal suture; mzmf, medial zygomatic frontal suture; cd, condylion, the hightest point of mandibular condyle; za, most lateral point of zygomatic arch; ma, lowest point of mastoid process; ag, antegonion, the highst point of antegonial notch; mx, maxillare, the line between maxillary alveolar process and inferior point of ztgomatic buttress. Similar with J point; J jugulare (J), the most concave point of zygomatic buttress; um, maxillary molar, the outer surface of the maxillary first molar; lm, mandibular molar, the outer surface of the mandibular first molar; mf, mental foramen; CSP, cental sagittal plan. Draw in several ways, representative example, vertical line of lo-lo line is passing through plotting the om, passing drawing a vertical line of the line connecting the two sides lzmf and zmmf is om.
