Learning Objective: At the end of this session, the learner will be able to describe the anatomy of the maxilla, including its structure, surfaces, processes, and foramina, and explain its clinical significance in facial fractures, particularly the Le Fort classification.
The maxilla is a paired, pyramidal-shaped bone that forms the upper jaw and the central structure of the midface. It supports the upper teeth, contributes to the formation of the orbits, nasal cavity, and hard palate, and houses the maxillary sinus, the largest of the paranasal sinuses.
Anatomical Structure
Each maxilla consists of:
- A body (pyramidal in shape)
- Four processes:
- Zygomatic process
- Frontal process
- Palatine process
- Alveolar process
The body has four surfaces — anterior, orbital, infratemporal, and nasal — each with distinctive anatomical landmarks.
The Body of the Maxilla
Infratemporal Surface
- Forms the anterior wall of the infratemporal fossa.
- Contains the maxillary tuberosity, which bears the alveolar foramina.
- These foramina transmit the posterior superior alveolar nerve and vessels to the upper molar teeth.
Orbital Surface
- Contributes to the floor of the orbit.
- Articulates with:
- Lacrimal bone
- Orbital plate of the ethmoid
- Orbital process of the palatine bone
- Key landmarks:
- Infraorbital groove → continues as the infraorbital canal
- Infraorbital foramen → transmits infraorbital nerve and vessels
- Infraorbital margin → attachment for orbicularis oculi
Nasal Surface
- Forms the lateral wall of the nasal cavity and the medial wall of the maxillary sinus.
- Contains:
- Maxillary ostium → opening for sinus drainage into the nasal cavity
- Nasolacrimal groove → forms part of the nasolacrimal canal
- Conchal crest → articulates with the inferior nasal concha
Anterior Surface
- Triangular in shape, it forms the front of the upper jaw.
- Features:
- Canine eminence → raised area over the canine tooth root
- Incisive fossa (medial to eminence)
- Canine fossa (lateral to eminence; origin for levator anguli oris)
- Infraorbital foramen → exit of the infraorbital canal
Maxillary Sinus
- Largest paranasal sinus (10–15 mL).
- Pyramidal in shape:
- Base: lateral wall of the nasal cavity
- Apex: directed toward the zygomatic process
- Roof: floor of the orbit
- Floor: alveolar process (closely related to upper molar roots)
- The maxillary ostium opens into the semilunar hiatus beneath the middle nasal concha for drainage.
Maxillary Processes
| Process | Description | Articulations / Key Features |
|---|---|---|
| Zygomatic process | Lateral projection forming part of the cheekbone | Articulates with the zygomatic bone |
| Frontal process | Extends superiorly to articulate with the frontal bone | Forms part of the nasal bridge and lacrimal groove |
| Palatine process | The medial projection forms most of the hard palate | Contains the incisive foramen for the nasopalatine nerve |
| Alveolar process | Inferior horseshoe-shaped projection | Houses the sockets for the upper teeth |
Alveolar Process
- Supports the upper teeth and contains dental alveoli (tooth sockets).
- Divided by:
- Interalveolar septa (between teeth)
- Interradicular septa (within roots of multi-rooted teeth)
- The external surface shows alveolar yokes, representing bony prominences over tooth roots.
Clinical Relevance
Facial (Midface) Fractures – Le Fort Classification
- Fractures of the maxilla are common due to its central facial position. The Le Fort system classifies midface fractures into three types:
| Type | Fracture Line | Key Features |
|---|---|---|
| Le Fort I (Horizontal) | Above the upper teeth, separating the alveolar and palatine processes | Floating palate |
| Le Fort II (Pyramidal) | From the nasal bridge → infraorbital margin → maxillary sinus | Infraorbital nerve injury, midface mobility |
| Le Fort III (Craniofacial disjunction) | Through the zygomatic arch, the orbital floor, nasofrontal suture | Midface separation from the skull base |
