Piriform aperture: anatomy of the base of the nose
- Highlighted area
Quick facts
- Definition
- Pear-shaped bony opening at the front of the skull that leads into the nasal cavity.
- Boundaries
- Nasal bones above; maxillae at the sides and base, with the anterior nasal spine at the center of the base.
- With aging
- Tends to widen and recede, especially at the bottom and sides.
- Effect on the face
- Less support for the base of the nostril wing and for the upper lip and nasolabial fold.
- Relevance in orofacial harmonization (HOF)
- Helps explain why the nasolabial fold deepens next to the nostril wing.
The piriform aperture is the pear-shaped bony opening at the center of the facial skeleton, where the nasal cavity opens to the front. It is formed by the nasal bones, above, and by the maxillae, at the sides and base, where the anterior nasal spine sits. The cartilaginous part and the soft tissues of the nose attach around it. In orofacial harmonization (HOF), it matters because the bone in this region supports the base of the nostril wing, the upper lip and the start of the nasolabial fold.
What are the boundaries of the piriform aperture?
| Boundary | Structure | What to look for |
|---|---|---|
| Superior | Nasal bones | Continue into the cartilaginous dorsum through the nasal cartilages |
| Lateral | Edge of the maxilla | Supports the base of the nostril wing |
| Inferior | Maxillae, with the anterior nasal spine | Support for the columella and the base of the upper lip |
Around the lateral and inferior edge lie the origins of muscles of the lip and nose, such as the levator labii superioris alaeque nasi and the nasalis muscle, plus a small deep space next to the base of the nostril wing, described in applied anatomy as the deep piriform space.
What changes with aging?
The facial skeleton ages too. In the central region, the piriform aperture tends to widen and its lower and lateral edge tends to recede, along with remodeling of the maxilla and premaxilla. The visible effect is usually:
- A more recessed nostril wing base, making the nose look more "drooping" or wider at the base.
- A deeper start of the nasolabial fold, next to the nostril wing, added to the change in the fat of the nasolabial compartment.
- An altered nasolabial angle, because of less support for the columella and the lip.
This bone recession explains why, in some patients, smile lines have a component of lack of deep support, and not only of skin and fat. In others, laxity predominates, and the reading changes.
Why does it matter in orofacial harmonization (HOF)?
The base of the nose is assessed when planning the nasolabial fold, the upper lip and nonsurgical rhinoplasty. Understanding that part of the depression comes from bone helps explain to the patient why the region changes with age and why the result varies from person to person.
How does it show up in the assessment?
- Basal and profile view: position of the nostril wing base relative to the lip and cheek.
- Nasolabial fold at rest and when smiling: separating lack of support from excess skin.
- Symmetry of the nostril wings: differences in the base between the sides.
Reading the midface layer by layer is covered in facial aging by layers.
Also known as: anterior nasal aperture, apertura piriformis, bony base of the nose.
Frequently asked questions
Are the piriform aperture and the piriform fossa the same thing?
Not exactly. The piriform aperture is the bony opening of the nose in the skull. In anatomy, the piriform fossa or recess is a structure of the larynx; in orofacial harmonization (HOF), however, many people call the depression beside the base of the nostril wing, over the maxilla, the piriform fossa.
Why does the base of the nose sink with age?
In part because the piriform aperture widens and the surrounding maxilla recedes with bone aging. With less support, the base of the nostril wing and the start of the nasolabial fold tend to look deeper.