Stomion: where the lips meet in facial analysis
Quick facts
- Definition
- The point where the upper and lower lips meet, at the center of the oral fissure.
- Where it is
- On the midline, between the upper and lower vermilion.
- Role in the face
- Divides the lower third into the part between subnasale and stomion and the part between stomion and chin.
- Clinical use
- Basis for measuring incisor display at rest and lip proportion.
- Variation
- It can be described as upper or lower when the lips are slightly parted.
The stomion is a landmark of facial analysis: the central point where the upper lip meets the lower lip, on the midline, with the mouth at rest. It marks the center of the oral fissure and works as a divider of the lower third of the face, which makes it useful both in assessing proportions and in planning lips and smile.
Where does the stomion sit in the lower third?
The lower third runs from the subnasale to the chin. The stomion divides that segment into two parts: the upper one, from subnasale to stomion, and the lower one, from stomion to chin. A classic reference, described in proportion analyses, is that the lower part is about twice the upper one. That ratio is a starting point and not a goal to be reached: harmonious faces vary widely and the assessment is always individual.
When is it used in practice?
- Incisor display at rest: the measurement between the upper stomion and the edge of the teeth, linked to a youthful smile and discussed in incisor display.
- Lip proportion: the relationship between upper and lower lip, described in lip proportion.
- Mouth symmetry: a deviation of the stomion from the midline suggests lip or jaw asymmetry.
- Documentation: a reference for recording photos at rest and confirming that the expression was neutral.
What the stomion does not tell you
On its own, the stomion does not show whether a procedure is needed. It only gains meaning together with other points, such as the commissures, the Cupid's bow and the chin. A measurement outside a "norm" is not a diagnosis, and the decision to recommend a treatment or not depends on the patient's concern, the anatomy and the judgment of the qualified professional, according to the rules of their professional board. Related points appear in facial landmarks and the line between the commissures is described in intercommissural line.
In Harmy
The Lips point of the app's marking guides the conversation about lip volume and proportion. Harmy does not measure the stomion or tooth display: the projection is an illustration, and the analysis of proportions remains the professional's job.
Also called: stomion point, lip junction.
Frequently asked questions
Is the stomion in the same place with the mouth open and closed?
Not exactly. With the lips sealed there is a single meeting point; with the mouth slightly open, an upper and a lower stomion are described, and the measurement should be taken with the lips at rest.