Gnathion
Pronunciation: NAY-thee-on
The most inferior and anterior point on the mandibular symphysis, used as a landmark in cephalometric tracing.
Full Definition
Gnathion is a constructed cephalometric landmark located at the most anterior and inferior point of the bony chin, situated midway between Pogonion and Menton along the symphyseal outline. It is frequently used in facial height calculations and assessments of lower facial morphology. Editors must distinguish it from the adjacent soft-tissue and hard-tissue chin landmarks, which are named differently. It is abbreviated Gn in cephalometric notation. Its misidentification in reports can lead to incorrect facial analysis conclusions.
Usage
Usage note: Always italicise or capitalise as a proper cephalometric landmark name. Do not confuse with Menton (most inferior point only) or Pogonion (most anterior point only).
In Context
- "The facial axis angle was measured from Basion to Gnathion relative to the Pterygomaxillary vertical." — Cephalometric analysis report
- "Care should be taken not to substitute Gnathion for Menton when reporting lower anterior facial height." — Editorial style note