Maxilla

The maxillae (or maxillary bones) are a pair of symmetrical bones joined at the midline, which form the middle third of the face. Each maxilla forms the floor of the nasal cavity and parts of its lateral wall and roof, the roof of the oral cavity, contains the maxillary sinus, and contributes most of the inferior rim and floor of the orbit.  It bears the upper tooth-bearing alveolar process.

The maxilla is sometimes called the upper jaw, usually in relation to the dentition.

Gross anatomy

The body of the maxilla is roughly pyramidal and has four surfaces that surround the maxillary sinus, the largest paranasal sinus: anterior, infratemporal (posterior), orbital and nasal. It also has four processes: zygomatic, frontal, alveolar, and palatine. It articulates with the following bones: frontal, ethmoid, nasal, zygomatic, lacrimal, middle nasal concha, inferior nasal concha, palatine, and vomer.

Anterior surface

• has vertical protrusions overlying the roots of the teeth, with the canine eminence being the most prominent of these

• the incisive fossa runs medial to the eminence and the canine fossa is lateral to it

• above the canine fossa lies the infraorbital foramen, which transmits the infraorbital vessels and nerve

• above the infraorbital foramen lies the maxillary part of the infraorbital margin

• the anterior nasal spine is a vertical midline protuberance, with the nasal notch forming its deeply concave lateral border

Infratemporal surface

• forms the anterior wall of the infratemporal fossa

• on the inferior aspect of the lateral margin, there may be a maxillary tuberosity, that appears after the appearance of the wisdom teeth

Orbital surface

• triangular in shape; forms most of the orbital floor

• articulates with lacrimal bone, orbital plate of ethmoid, and the orbital process of palatine bone

• posterior border forms most of the anterior edge of the inferior orbital fissure

• infraorbital groove passes centrally, transmits infraorbital vessels and nerve, and continues anteriorly as infraorbital canal, which opens into the infraorbital foramen

• the canalis sinuosus, which transmits the anterior superior alveolar nerve and vessels, branches off of the infraorbital canal

Nasal surface

• maxillary ostium opens from the maxillary sinus into hiatus semilunaris

• nasolacrimal groove is anterior to the ostium; comprises two-thirds of the nasolacrimal canal circumference

• conchal crest articulates with inferior nasal concha

Zygomatic process

• pyramid-shaped projection at which anterior, infratemporal and orbital surfaces converge

Frontal process

• located between the nasal and lacrimal bones

• contributes to the lacrimal fossa

• its medial surface is part of the lateral nasal wall

• closes anterior ethmoidal air cells

• articulates posteromedially with the middle nasal concha, superiorly with the nasal part of the frontal bone, posterolateral with the lacrimal bone, and anteromedially with the nasal bone

Alveolar process

• contains eight sockets (alveoli) on each side for upper teeth

• alveolus for the canine tooth is the deepest

Palatine process

• horizontal; projects medially from the lowest part of the medial aspect of the maxilla

• superior surface forms most of the nasal floor

• inferior surface forms anterior three-fourths of the hard palate

• contains two grooves posterolaterally that transmit the greater palatine vessels and nerves; additionally, many vascular foramina and depressions for palatine glands

• midline incisive fossa behind incisor teeth

• intermaxillary palatal suture runs posterior to the fossa

• two lateral incisive canals from the nasal cavity open in the incisive fossa and transmit terminations of the greater palatine artery and nasopalatine nerve

See also

• Le Fort fracture classification

• tripod fracture