maxilla

This article is about the human maxilla. For arthropod maxillae, see Mouthparts; for insect maxillae in particular, see Insect mouthparts.

Bone: Maxilla
Side view. Maxilla visible at bottom left, in green.
Front view. Maxilla visible at center, in yellow.
Gray's	subject #38 157
Precursor	1st branchial arch[1]
MeSH	Maxilla
Dorlands / Elsevier	Maxilla

The maxilla (plural: maxillae), also known as the mustache bone, is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible (lower jaw), which is also a fusion of two halves at the mental symphysis. Sometimes (e.g. in bony fish), the maxilla is sometimes called "upper maxilla", with the mandible being the "lower maxilla". Conversely, in birds the upper jaw is often called "upper mandible".

Function

The alveolar process of the maxilla holds the upper teeth, and is referred to as the maxillary arch. The maxilla attaches laterally to the zygomatic bones (cheek bones).

The maxilla assists in forming the boundaries of three cavities:

• the roof of the mouth
• the floor and lateral wall of the nasal antrum
• the floor of the orbit

The maxilla also enters into the formation of two fossae: the infratemporal and pterygopalatine, and two fissures, the inferior orbital and pterygomaxillary.

Components

Each half of the fused maxilla consists of:

• The body of the maxilla
• Four processes
  • The zygomatic process
  • The frontal process
  • The alveolar process
  • The palatine process
• Infraorbital foramen
• The maxillary sinus

Articulations

The maxilla articulates with nine bones:

• two of the cranium: the frontal and ethmoid
• seven of the face: the nasal, zygomatic, lacrimal, inferior nasal concha, palatine, vomer, and the adjacent fused maxillary bone.

Sometimes it articulates with the orbital surface, and sometimes with the lateral pterygoid plate of the sphenoid.

In other animals

In most vertebrates, the foremost part of the upper jaw, to which the incisors are attached in mammals consists of a separate pair of bones, the premaxillae. These fuse with the maxilla proper to form the bone found in humans, and some other mammals. In bony fish, amphibians, and reptiles, both maxilla and premaxilla are relatively plate-like bones, forming only the sides of the upper jaw, and part of the face, with the premaxilla also forming the lower boundary of the nostrils. However, in mammals, the bones have curved inward, creating the palatine process and thereby also forming part of the roof of the mouth.^[2]

Birds do not have a maxilla in the strict sense; the corresponding part of their beaks (mainly consisting of the premaxilla) is called "upper mandible".

Cartilagenous fish, such as sharks, also lack a true maxilla. Their upper jaw is instead formed from a cartilagenous bar that is not homologous with the bone found in other vertebrates.^[2]

Additional images

The seven bones which articulate to form the orbit.	Facial bones.	Left maxilla. Outer surface.	Left maxilla. Nasal surface.
Left maxillary sinus opened from the exterior.	The bony palate and alveolar arch.	Sphenoid bone visible center right.	Articulation of left palatine bone with maxilla.
Side view of the teeth and jaws.

See also

• Bone terminology
• Terms for anatomical location
• Ossification of maxilla
• Hypostome
• Maxillofacial surgery

References

This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (December 2007)

External links

• SUNY Labs 22:os-1901

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.

v • d • e The Bones which form the Orbit Frontal bone • Zygomatic bone • Maxillary bone • Sphenoid bone • Ethmoid bone • Palatine bone • Lacrimal bone