Maxilla

At a glance

English

Maxilla

Latin (TA2)

Maxilla

System

Bone

Region

Head

Side

Paired, left and right

About the maxilla

Each maxilla is one of a pair of bones that together make the upper jaw and the middle of the face. The two meet in the midline at the intermaxillary suture, and at the lower edge of the nasal opening they project forward as the anterior nasal spine. Unlike the mandible, which moves, the maxillae are fixed to the rest of the skull. Each one helps build the floor of the orbit, the floor and lateral wall of the nasal cavity, the front of the hard palate and the sockets of the upper teeth.

The bone has a hollow, roughly pyramidal body and four processes. The body contains the maxillary sinus, the largest of the paranasal sinuses. Its front surface faces the cheek and carries the infraorbital foramen just below the orbital rim, its upper surface forms most of the orbital floor with the infraorbital groove running across it, and its back surface ends in the rounded maxillary tuberosity behind the last molar. The frontal process rises beside the nose to the frontal bone, the zygomatic process reaches out to the cheek bone, the alveolar process curves below to hold the teeth, and the palatine process is a horizontal shelf that meets its partner to form the front three-quarters of the hard palate.

The maxilla meets the frontal, ethmoid, nasal, lacrimal, zygomatic, palatine and vomer bones, the inferior nasal concha and the opposite maxilla. It forms in membrane early in fetal life. At birth the sinus is small and the jaw shallow; the bone deepens as the teeth develop and erupt, and the sinus expands into the space they leave as the face lengthens.

Clinically, the maxilla is involved in many facial fractures, classically along the Le Fort lines that separate the tooth-bearing part, the central face or the whole facial skeleton from the skull. Failure of the palatine processes and the front of the jaw to fuse before birth gives cleft palate or cleft lip. The roots of the upper premolars and molars lie just under the sinus floor, so tooth infections can spread into the sinus, and an extraction can open a passage into it. Fractures of the orbital floor often damage the infraorbital nerve, numbing the cheek and upper lip.

Function and supply

Function

Holds the upper teeth and carries chewing forces up into the skull, and shapes the middle of the face, the floor of the orbit, the nasal cavity and the front of the palate.

Nerve supply

The infraorbital nerve and the superior alveolar nerves, from the maxillary division of the trigeminal nerve, supply the bone, upper teeth, gums and sinus; the nasopalatine and greater palatine nerves supply the palate.

Blood supply

Branches of the maxillary artery, chiefly the infraorbital, superior alveolar and greater palatine arteries, with facial artery branches to its outer surface.