The maxillary bone: morphology

The Maxillary bone, with its contralateral counterpart, forms  most of the upper facial skull bones. Although being the largest bone on the face, it is proportionately the lightest, because it is hollowed out by a large pneumatic cavity: the maxillary sinus. The maxilla is a bone of membranous origin, belonging to the viscerocranium.

1. position and surroundings of the maxillary bone

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The maxilla is in direct relation with the bones of the superior facial mass (palatine, zygomatic, nasal, lacrimal, inferior nasal turbinate and vomer) and the bones of the anterior level of the base of the skull such as the frontal and the ethmoid . It is related to the sphenoid through the palatine at the level of the pterygoid processes. This bone participates in the formation of the orbital and nasal cavities and the infratemporal and pterygopalatine pits. It participates, through its palatal process which articulates with the horizontal blade of the palatine, in the formation of the bony palate.

Maxilla, maxillary bone, Jawbone
Figure 1: Diagram of an external view of the maxilla in relation to the bones of the skull.
The maxilla -1- is the central element of the superior facial mass. He
participates, by articulating with the nasal bones -2-, the zygomatic bone -3-
and the frontal bone -4-, to the formation of the nasal and orbital cavities. (1)

2.General morphology of the maxillary bone

2.1. Superior or orbital surface

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Very thin and often translucent, it forms most of the lower wall of the orbital cavity. She looks slightly down, forward and out. It is smooth and triangular. It is continued behind by the orbital process of the palatine which completes this face. Its posterior half is marked by the infraorbital groove which then continues through the infraorbital duct, and ends at the level of the infraorbital foramen. It is in the infraorbital duct that the superior anterior and middle alveolar nerves originate.

2.2. Anterolateral or jugal face

Oriented forwards and outwards, this face is slightly concave. It is easily palpable under the skin. It is marked by the infraorbital foramen, framed above by the insertion of the levator muscle of the upper lip and the wing of the nose and below by the insertion of the levator muscle of the oral angle. The root of the canine forms a protrusion: the jugum of the canine. At the level of the roots of the incisors, the bony concavity gives insertion to the depressor muscle of the nasal septum. The bone wall is reduced to a thin film of bone within which the superior anterior alveolar pedicle travels

2.3. Posterolateral or infratemporal face

This wall is subdivided into two portions:

• Anterior and lateral: is slightly concave, forms with the zygomatic bone the maxillo-zygomatic fossa and corresponds to the anterior part of the fatty body of the cheek.

• Posterior: corresponds to the maxillary tuberosity which separates the maxillary sinus from the infratemporal fossa, behind and outside, and from the pterygopalatine fossa behind. It articulates above with the orbital process of the palatine, below with the pyramidal process of the palatine, and posteriorly with the pterygoid process of the sphenoid. This wall contains the superior-posterior alveolar vessels and nerves, the bony branches of which enter through the posterior and superior alveolar foramina. On the surface, pressed between the periosteum and the buccinator aponeurosis, the mucous and muscular threads of the postero-superior alveolar pedicle travel. In its posterior superior part, the tuberosity is marked by the bend that the maxillary artery makes before entering the pterygomaxillary fissure. The pterygoid muscles, lateral and medial, are inserted on the postero-inferior part of the tuberosity and the maxillary insertions of the buccinator muscle on the lateral face of the alveolar wall opposite the molars.

2.4. Peak of the Maxillary bone

With a superolateral orientation, it constitutes the zygomatic process, the truncated end of which articulates with the zygomatic bone. The zygomatic process is the lateral prolongation of the three faces of the Maxillary bone.

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