Maxillae

1. Overview

The maxillae are a pair of bones that form the upper jaw and a major portion of the facial skeleton. They play a key role in supporting the upper teeth, forming the orbit of the eye, the walls of the nasal cavity, and the hard palate. The two maxillae fuse at the midline during development, creating the foundation for much of the midface. These bones are critical for functions such as mastication, respiration, speech, and facial aesthetics.

2. Location

The maxillae are located in the central part of the facial skeleton:

• Superiorly: Contribute to the floor of the orbits (eye sockets).

• Inferiorly: Form the roof of the oral cavity and house the upper dental arch.

• Medially: Border the nasal cavity and articulate with the opposite maxilla at the intermaxillary suture.

• Laterally: Articulate with the zygomatic bones (cheekbones).

3. Structure

Each maxilla is an irregularly shaped bone made up of a body and four processes:

• Body of the maxilla: Contains the maxillary sinus, a large air-filled cavity.

• Frontal process: Projects upward to articulate with the frontal bone.

• Zygomatic process: Extends laterally to meet the zygomatic bone.

• Alveolar process: Contains sockets (alveoli) for the upper teeth.

• Palatine process: Projects horizontally to form the anterior three-quarters of the hard palate.

Important anatomical features:

• Infraorbital foramen: Transmits the infraorbital nerve and vessels.

• Canine fossa: A depression just above the canine tooth.

• Maxillary sinus: The largest paranasal sinus, within the body of the maxilla.

4. Function

The maxillae serve multiple structural and functional purposes:

• Support the upper teeth: The alveolar processes hold the upper dental arch in place.

• Form key facial structures: Contribute to the nose, orbit, and mouth architecture.

• Anchor facial muscles: Serve as attachment points for muscles of facial expression and mastication.

• Facilitate air flow and speech: Help construct the oral and nasal cavities and hard palate.

5. Physiological role(s)

The maxillae play important roles beyond bone structure:

• Respiration: Form the floor of the nasal cavity and house the maxillary sinuses, which warm and humidify inhaled air.

• Speech production: Help form the roof of the mouth and nasal passages essential for proper resonance and articulation.

• Growth and development: Guide the eruption of teeth and the development of the midface during childhood and adolescence.

• Facial contour and aesthetics: Influence the prominence of the cheeks, nasal base, and upper lip support.

6. Clinical Significance

The maxillae are involved in various clinical conditions and surgical considerations:

• Maxillary fractures:

  • Common in facial trauma; Le Fort fractures describe classic fracture patterns involving the maxilla (I, II, and III).

  • Can lead to occlusion issues, sinus disruption, and cosmetic deformity.

• Cleft palate and cleft lip:

  • Congenital defects due to improper fusion of the maxillary processes; require surgical correction.

• Maxillary sinusitis:

  • Infection or inflammation of the maxillary sinus can cause facial pain, nasal congestion, and referred dental discomfort.

• Dental implications:

  • Tooth loss, infections, or abscesses in the upper teeth can affect the maxillary bone and sinus.

  • Implant placement in the maxilla may require sinus lift procedures.

• Orthognathic surgery:

  • Maxillary repositioning may be performed for malocclusion, facial asymmetry, or obstructive sleep apnea.