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Superior wall of the maxillary sinus

The superior wall of the maxillary sinus forms the roof of the maxillary sinus and corresponds anatomically to the floor of the orbit. It is a thin bony plate that separates the maxillary sinus from the orbital contents and is of major importance in radiology, maxillofacial surgery, otolaryngology, and trauma assessment.

Because of its close relationship to the orbit and infraorbital neurovascular structures, this wall is frequently evaluated in sinus disease, orbital complications, and facial fractures.

Synonyms

  • Roof of the maxillary sinus

  • Orbital floor (sinus-related portion)

Location

  • Forms the superior boundary of the maxillary sinus

  • Corresponds to the inferior wall (floor) of the orbit

  • Extends from the anterior maxillary wall posteriorly toward the pterygopalatine region

  • Situated inferior to the orbital contents

  • Superior to the air-filled cavity of the maxillary sinus

Anatomical components

  • Thin cortical bone of the maxilla

  • Infraorbital canal and groove:

    • Transmits the infraorbital nerve and vessels

  • Orbital periosteum (periorbita) on the superior surface

  • Maxillary sinus mucosa on the inferior surface

Relations

Superiorly:

  • Orbital cavity

  • Inferior rectus muscle

  • Orbital fat

  • Infraorbital nerve and vessels

Inferiorly:

  • Maxillary sinus cavity

  • Schneiderian membrane (sinus mucosa)

Anteriorly:

  • Anterior wall of the maxillary sinus

  • Inferior orbital rim region

Posteriorly:

  • Posterior maxillary wall

  • Pterygopalatine fossa (near posterior extent)

Medially:

  • Medial wall of the maxillary sinus

  • Inferior turbinate region (indirect relationship)

Laterally:

  • Zygomatic process of the maxilla

X-ray appearance

Waters (occipitomental) view:

  • Superior sinus margin: Smooth curvilinear bony outline

  • Orbital floor: Seen as a thin radiopaque line above the sinus

  • Maxillary sinus: Radiolucent air-filled cavity beneath the wall

  • Infraorbital canal: Occasionally visible as a linear lucency

CT appearance

Non-contrast CT:

  • Superior wall: Thin, continuous hyperdense bony plate

  • Orbital floor: Clearly delineated from sinus cavity

  • Infraorbital canal: Well-visualized osseous tunnel within the wall

  • Sinus cavity: Air density inferior to the wall

Post-contrast CT:

  • Bone: No enhancement

  • Adjacent soft tissues: Normal enhancement of orbital structures

  • Sinus mucosa: Thin non-enhancing lining if present

3D CT VRT appearance

Volume-rendered technique (VRT):

  • Orbital floor contour: Smooth and concave toward the sinus

  • Superior sinus boundary: Clearly defined roof surface

  • Infraorbital canal: Subtle surface impression or ridge

  • Utility: Excellent for evaluating bony integrity and spatial relationships

MRI appearance

T1-weighted images:

  • Bony wall: Low signal intensity

  • Orbital fat: High signal superior to the wall

  • Sinus cavity: Low signal (air)

T2-weighted images:

  • Bone: Low signal

  • Orbital contents: Intermediate-to-high signal

  • Sinus cavity: Signal void from air

CT image

ct Superior Wall of Maxillary Sinus anatomy image -img-00000-00000

X-Ray image

x ray Superior wall of maxillary sinus