Upper Jaw Bone
Maxilla
location_on Central face, forming the upper jaw, orbital floor, nasal cavity floor, and hard palate
The maxilla is the second largest bone of the face, forming the upper jaw, the floor of the orbit, the lateral wall and floor of the nasal cavity, and most of the hard palate. Each maxilla contains a large maxillary sinus, the largest paranasal sinus. The paired maxillae articulate in the midline and with nine other bones, making them central to facial architecture.
Key Anatomical Features
- Maxillary sinus (antrum of Highmore) is the largest paranasal sinus occupying the body
- Infraorbital foramen transmits the infraorbital nerve, providing sensation to the cheek and upper lip
- Alveolar process houses the sockets for the upper 16 teeth
- Palatine process forms the anterior three-quarters of the hard palate
- Frontal process ascends to articulate with the frontal and nasal bones
Muscle Attachments
| Muscle | Attachment | Action |
|---|---|---|
| Orbicularis oris | Incisive fossa region of maxilla | Closes and purses the lips |
| Levator labii superioris | Below infraorbital foramen | Elevates the upper lip |
| Levator anguli oris | Canine fossa below infraorbital foramen | Elevates the angle of the mouth |
| Buccinator | Alveolar process of maxilla | Compresses the cheek against teeth during chewing |
| Masseter (origin, indirectly) | Zygomatic process of maxilla | Assists in jaw elevation |
Joints and Articulations
| Joint | Type | Connects to |
|---|---|---|
| Intermaxillary suture | Fibrous suture | Opposite maxilla |
| Zygomaticomaxillary suture | Fibrous suture | Zygomatic bone |
| Palatomaxillary suture | Fibrous suture | Palatine bone |
Common Pathologies
Le Fort fractures
Classified midfacial fractures involving the maxilla. Le Fort I separates the alveolar process; Le Fort II creates a pyramidal fracture; Le Fort III separates the entire midface from the cranium.
Maxillary sinusitis
Infection of the maxillary sinus, the most common paranasal sinus to become infected. Proximity of upper molar roots to the sinus floor means dental infections can cause sinusitis and vice versa.
Cleft palate
Failure of fusion of the palatine processes of the maxillae during weeks 6 to 12 of fetal development, resulting in an opening between the oral and nasal cavities.
Oroantral fistula
Abnormal communication between the oral cavity and maxillary sinus, usually following extraction of upper molar teeth whose roots extend into the sinus.
Clinical Relevance
The roots of the upper premolar and molar teeth are often separated from the maxillary sinus by only a thin layer of bone, or may even project into the sinus. This proximity means dental infections can cause sinusitis and tooth extractions can create oroantral communications. Le Fort fracture classification is essential knowledge for facial trauma management. Le Fort II and III fractures can involve the skull base.
Development and Ossification
The maxilla ossifies intramembranously from a single center that appears above the canine tooth region during the 6th fetal week. Growth occurs through surface apposition and sutural growth. The maxillary sinus is present at birth as a small cavity and continues to enlarge until the late teens with eruption of the permanent teeth.
Did You Know?
- The maxillary sinus is present at birth but is only about the size of a small pea
- The maxilla is one of the few bones that contributes to four different cavities: oral, nasal, orbital, and the sinus itself
- Upper molar roots sometimes project directly into the maxillary sinus with no bony floor separating them
Scan this bone yourself
Download Osteo+ and identify the upper jaw bone instantly with your camera. Get all the details above and more from a single photo.