Nasion: the root-of-the-nose point in facial analysis

The nasion is the point at the root of the nose, on the midline, between the forehead and the nasal dorsum. Anatomy describes two nasions: the bony nasion, where the frontonasal suture (between the frontal bone and the nasal bones) crosses the median plane, and the soft tissue nasion, the deepest point of the concavity between the forehead and the nose when the face is seen in profile. In HOF, the soft tissue one is used in clinical and photographic assessment of the nose.

Bony nasion and soft tissue nasion: what is the difference?

The two do not coincide exactly: the thickness of the soft tissues at the root of the nose varies, and the skin point usually sits slightly forward and at a height close to the bony one. In general, the height of the soft tissue nasion is described near the level of the upper eyelid crease, with the eye open and looking straight ahead, but there is variation between people and ethnicities.

How does the nasion enter nose analysis?

• Nasofrontal angle: the nasion is the vertex of the nasofrontal angle, formed by the tangent of the glabella and the tangent of the nasal dorsum.
• Root height and projection: the assessment looks at whether the root is high or low and how far it projects in front of the eye line.
• Dorsal line: the position of the nasion changes how a hump reads. A recessed nasion makes the dorsum look higher; that is why nonsurgical rhinoplasty sometimes works on the root to soften the transition, at the professional's discretion.
• Division into thirds: some authors use the nasion, and others the glabella, as the boundary between the upper third and the midface. It is worth recording which reference was used, as explained in facial assessment by thirds.

Why is the nasion an area of caution?

The root of the nose concentrates vessels of the network linked to the ophthalmic system: the dorsal nasal artery, branches of the supratrochlear artery and the angular artery network, near the inner corner of the eye. The skin is relatively thick at the nasion and becomes thinner toward the rhinion, which changes tolerance to volume and the visibility of irregularities.

How does it show up in the assessment?

• Standardized profile photo: head in the Frankfurt position, without tilting, so that the nasofrontal angle is comparable between visits. See standardized clinical photography.
• History: rhinoplasty, nasal fracture or previous filler at the root change the anatomy and the vascular map.
• Relation to the forehead: a very projected or very flat glabella changes the perception of the nasion, even without any change in the nose.
• Midline: deviation of the root relative to the facial midline shows better in the frontal photo.

Also called: nasion, N point, nasion point, nasal root (in clinical use).