Maxilla

In vertebrates, the maxilla (pl.: maxillae /mækˈsɪliː/) 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 two maxillary bones are fused at the intermaxillary suture, forming the anterior nasal spine. This is similar to the mandible (lower jaw), which is also a fusion of two mandibular bones at the mandibular symphysis. The mandible is the movable part of the jaw.

The maxilla is a paired bone - the two maxillae unite with each other at the intermaxillary suture. The maxilla consists of:

It has three surfaces:

Features of the maxilla include:

Each maxilla articulates with nine bones: frontal, ethmoid, nasal, zygomatic, lacrimal, and palatine bones, the vomer, the inferior nasal concha, as well as the maxilla of the other side.

Sometimes it articulates with the orbital surface, and sometimes with the lateral pterygoid plate of the sphenoid.

The maxilla is ossified in membrane. Mall and Fawcett maintain that it is ossified from two centers only, one for the maxilla proper and one for the premaxilla.

These centers appear during the sixth week of prenatal development and unite in the beginning of the third month, but the suture between the two portions persists on the palate until nearly middle life. Mall states that the frontal process is developed from both centers.