The maxilla forms the upper jaw by fusing together two irregularly-shaped bones along the median palatine suture, located at the midline of the roof of the mouth. The maxillary bones on each side join in the middle at the intermaxillary suture, a fused line that is created by the union of the right and left ‘halves’ of the maxilla bone, thus running down the middle of the upper jaw. The bones help to form the upper jaw, sub-segments of the eye sockets, and the lower sections and sides of the nasal cavity. Additionally, they reduce the heaviness of the skull, help support the back teeth, and help to allow the voice to resonate.
Each half of the fused bones contains four processes. These include the zygomatic, frontal, palatine, and alveolar processes of the maxilla. They also contain the infraorbital foramen, an opening in the bone just below the eye sockets, and the maxillary sinus, which helps to protect important facial structures during an accidental trauma, like the crumple zone of a car.
A severe blow to the face can fracture the maxilla, causing the displacement of teeth, loss of feeling in the lips or cheeks, and a retraction of the eyeball. Surgery is required to repair the break, as well as reset the bone and surrounding bones.