Anterior nasal aperture

The Anterior Nasal Aperture (or piriform/pyriform aperture) is a heart-shaped or pyriform opening, whose long axis is vertical, and narrow end upward; in the recent state it is much contracted by the lateral and alar cartilages of the nose.

It is bounded above by the inferior borders of the nasal bones; laterally by the thin, sharp margins which separate the anterior from the nasal surfaces of the maxillæ; and below by the same borders, where they curve medialward to join each other at the anterior nasal spine.