[A new cephalometric analysis of the profile. 1. Anatomic bases, cephalometry]

Through a revision of the classical anatomy of the exocranial skull base, the authors present of a new exobasicranial plan in cephalometry, the Nasion-Glenion (or Porion plane). The median part of the base devoted to ventilation goes from the Nasion to the spheno-occipital synchondrosis, joining two essentially cartilaginous sites. The lateral parts, with manducatory functions, extend from supra-orbital rim to glenoid fossa and are mainly membranous. Pterygoid processes belong to the facial squeleton. Dental and growth axes are projected on the new exobasicranial base. Facial structures are analyzed in four planes, perpendicular to Francfort plane (facial cutaneous plane, premaxillary plane, postmaxillary plane, craniocervical plane).