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Posterior border of maxilla

The posterior border of the maxilla forms the posterior limit of the maxillary bone and plays a key role in separating the maxilla from the infratemporal and pterygopalatine fossae. It is anatomically important as it contributes to the anterior boundary of the pterygomaxillary fissure, a vertical cleft that provides communication between the infratemporal fossa and the pterygopalatine fossa.

This border is not a free margin but a structured posterior surface that serves as an attachment site for soft tissues and as a landmark for neurovascular pathways traversing the deep face. Its integrity is essential for normal midfacial architecture and serves as an important reference point in maxillofacial surgery and imaging.

Synonyms

  • Posterior surface of maxilla

  • Pterygomaxillary border of maxilla

Location and Structure

  • Position: Posterior aspect of the maxillary body.

  • Orientation: Vertically oriented surface forming the anterior wall of the pterygomaxillary fissure.

  • Extent:

    • Superiorly related to the posterior wall of the maxillary sinus.

    • Inferiorly continuous with the alveolar process posteriorly.

  • Surface features:

    • Relatively smooth cortical surface.

    • Contains small nutrient foramina.

    • Forms part of the boundary of deep facial spaces.

Relations

  • Posteriorly: Infratemporal fossa and pterygoid process of sphenoid

  • Medially: Posterior wall of the maxillary sinus

  • Laterally: Infratemporal surface of the maxilla

  • Superiorly: Inferior orbital fissure region (indirect relation)

  • Inferiorly: Posterior alveolar region of maxilla

Attachments

  • Muscular:

    • Posterior fibers of the buccinator muscle arise from adjacent maxillary regions

  • Ligamentous and fascial:

    • Pterygomaxillary region supports connective tissue planes of the deep face

  • Neurovascular proximity:

    • Close to posterior superior alveolar neurovascular bundles (without direct attachment)

Function

  • Forms a structural boundary between facial skeleton and deep facial spaces

  • Contributes to stability of the posterior maxilla

  • Serves as an anatomical landmark for surgical access to the pterygopalatine fossa

  • Helps define pathways for vessels and nerves passing through the pterygomaxillary fissure

Imaging Appearance

MRI Appearance

T1-weighted images:

  • Cortical bone: Very low signal (dark)

  • Cancellous bone (limited): Intermediate-to-bright signal due to fatty marrow

  • Adjacent maxillary sinus air: Signal void (black)

  • Surrounding soft tissues: Clear fat–muscle contrast

T2-weighted images:

  • Cortical bone: Low signal

  • Marrow: Intermediate-to-bright, slightly less than T1

  • Maxillary sinus air: Signal void

  • Adjacent soft tissues: Intermediate signal intensity

STIR:

  • Bone cortex: Dark

  • Normal marrow: Intermediate-to-dark signal

  • Surrounding soft tissues: Suppressed fat with uniform appearance

  • Maxillary sinus air: No signal

T1 Fat-Saturated Post-Contrast:

  • Cortical bone: No enhancement

  • Normal marrow: Mild homogeneous enhancement

  • Adjacent soft tissues: Uniform enhancement without focal abnormality

  • Clear delineation of posterior maxillary contour

CT Appearance

Non-Contrast CT:

  • Cortical bone: High attenuation, sharply defined

  • Posterior maxillary border: Smooth, continuous bony margin

  • Maxillary sinus: Air-filled cavity with thin posterior bony wall

  • Pterygomaxillary fissure: Clearly visualized vertical cleft posterior to maxilla

  • Excellent depiction of bone thickness and surface anatomy

Post-Contrast CT:

  • Bone cortex: No enhancement

  • Marrow spaces: Mild enhancement

  • Adjacent soft tissues: Homogeneous enhancement

  • Clear differentiation between maxilla and infratemporal soft tissues

X-Ray Appearance

  • Waters (occipitomental) view:

    • Posterior border seen indirectly as part of maxillary sinus outline

    • Appears as a smooth posterior sinus margin

  • Lateral skull view:

    • Posterior maxilla visualized as a dense vertical bony line anterior to pterygoid plates

  • Panoramic radiograph (OPG):

    • Posterior maxillary contour seen behind molar alveoli

OPG image

Posterior border of maxilla