The piriform aperture, pyriform aperture, or anterior nasal aperture, is a

pear Pears are fruits produced and consumed around the world, growing on a tree and harvested in the Northern Hemisphere in late summer into October. The pear tree and shrub are a species of genus ''Pyrus'' , in the family Rosaceae, bearing the p ...

-shaped opening in the

human skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...

. Its long axis is vertical, and narrow end upward; in the recent state it is much contracted by the

lateral nasal cartilage The lateral cartilage (upper lateral cartilage, lateral process of septal nasal cartilage) is situated below the inferior margin of the nasal bone, and is flattened, and triangular in shape. Its anterior margin is thicker than the posterior, and ...

and the greater and

lesser alar cartilages In human anatomy the part of the nose which forms the lateral wall is curved to correspond with the ala of the nose; it is oval and flattened, narrow behind, where it is connected with the frontal process of the maxilla The maxilla (plural: ...

of the

nose A nose is a protuberance in vertebrates that houses the nostrils, or nares, which receive and expel air for respiration alongside the mouth. Behind the nose are the olfactory mucosa and the sinuses. Behind the nasal cavity, air next passes th ...

. It is bounded above by the inferior borders of the

nasal bones The nasal bones are two small oblong bones, varying in size and form in different individuals; they are placed side by side at the middle and upper part of the face and by their junction, form the bridge of the upper one third of the nose. Eac ...

; laterally by the thin, sharp margins which separate the anterior from the nasal surfaces of the

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...

; and below by the same borders, where they curve medialward to join each other at the

anterior nasal spine The anterior nasal spine, or anterior nasal spine of maxilla, is a bony projection in the skull that serves as a cephalometric landmark. The anterior nasal spine is the projection formed by the fusion of the two maxillary bones at the intermaxill ...

References

Nose {{musculoskeletal-stub