|Precursor||median nasal prominence|
Other terms used for this structure include premaxillary bone or os premaxillare, and intermaxillary bone or os intermaxillare.
In the nasal cavity, the premaxillary element projects higher than the maxillary element behind.
The palatal portion of the premaxilla is a bony plate with a generally transverse orientation.
The incisive foramen is bound anteriorly and laterally by the premaxilla and posteriorly by the palatine process of the maxilla.
In the embryo, the nasal region develops from neural crest cells which start their migration down to the face during the fourth week of gestation.
The first ossification centers in the area of the future premaxilla appear during the seventh week above the germ of the second incisor on the outer surface of the nasal capsule.
After eleven weeks an accessory ossification center develops into the alar region of the premaxilla.
Then a premaxillary process grow upwards to fuse with the frontal process of the maxilla; and later expands posteriorly to fuse with the alveolar process of the maxilla.
The boundary between the premaxilla and the maxilla remains discernible after birth and a suture is often observable up to five years of age.
In bilateral cleft lip and palate, the growth pattern of the premaxilla differs significantly from the normal case; in utero growth is excessive and directed more horizontally, resulting in a protrusive premaxilla at birth.
Forming the oral edge of the upper jaw in most jawed vertebrates, the premaxillary bones comprise only the central part in more primitive forms.
Intriguingly the septomaxilla is still present in monotremes.
The differences in the size and composition in the premaxilla of various families of bats is used for classification.
Credits to the contents of this page go to the authors of the corresponding Wikipedia page: en.wikipedia.org/wiki/Premaxilla.