Gnathion
Definition
The most inferior point of the mandibular symphysis in the midline, corresponding to the tip of the chin in the portrait photograph. A primary landmark for superimposition alignment at the inferior face.
- Location
- Most inferior point of the mandibular symphysis, midline
- Corresponds to
- Tip of the chin externally
- Use
- Craniofacial superimposition landmark
- Category
- Cephalometric landmark point
Common questions
Why is gnathion useful specifically for photo-skull superimposition?+
It is a clearly defined bony midline point with a directly visible external counterpart, the chin tip, in a portrait photograph, making it one of the more reliable landmarks for aligning skull and facial images at the lower face.
Is gnathion used in other forensic anthropology methods besides superimposition?+
Yes, it is a standard craniometric landmark used in facial approximation, cephalometric analysis and measurements of mandibular and facial proportions, not exclusively in superimposition work.
What can affect the reliability of gnathion as a landmark?+
Soft tissue thickness over the chin varies between individuals and can shift with weight change or age, so while the bony gnathion point is fixed, its relationship to the visible chin surface in a photograph carries some individual variation.
Related terms
- Consistent with
- The categorical superimposition conclusion that examined morphological features do not exclude the skull as deriving from the same individual as the portrait....
- Exclusion
- The categorical conclusion that one or more examined features are clearly inconsistent in a way that cannot be explained by projection angle,...
- Frankfurt Horizontal Plane
- The anatomical reference plane defined by the upper border of the external acoustic meatus and the lowest point of the orbital margin...
- Glaister-Brash Method
- The original photographic-transparency superimposition protocol developed by John Glaister Jr and James Couper Brash for the 1935 Buck Ruxton case in Lancaster...
- Gonion
- The most posterior and inferior point of the mandibular angle, bilaterally. Used in superimposition to assess the width of the jaw angle...
- Iscan-Helmer 1993
- The edited volume 'Forensic Analysis of the Skull' (Iscan and Helmer, Wiley-Liss, 1993) that brought together the first systematic reliability assessment of...
- Nasion
- The anatomical landmark at the junction of the nasal bones and the frontal bone (the bridge of the nose). One of the...
- Photo-Skull Superimposition
- The forensic identification method of placing a life portrait photograph alongside or overlaid on a photograph of a recovered skull, aligning them...
- Video Superimposition
- The updated superimposition workflow using a motorised skull turntable, a calibrated video camera, and real-time electronic mixing of the skull video image...