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Superior wall of orbit

The superior wall of the orbit, also known as the orbital roof, forms the upper boundary of the orbital cavity and separates the orbit from the anterior cranial fossa. It is a thin but strong bony plate primarily formed by the orbital plate of the frontal bone, with a posterior contribution from the lesser wing of the sphenoid.

This wall provides structural protection to the orbital contents, including the globe, extraocular muscles, and neurovascular structures, while simultaneously supporting the frontal lobes of the brain superiorly. Its smooth inferior surface allows unhindered movement of orbital structures, whereas its superior surface supports the dura and frontal lobe gyri.

Synonyms

  • Orbital roof

  • Superior orbital wall

  • Roof of the orbit

Location and Structure

  • Position: Forms the superior boundary of the orbit between the frontal bone anteriorly and sphenoid bone posteriorly

  • Bones involved:

    • Orbital plate of frontal bone (major component)

    • Lesser wing of sphenoid (posterior component)

  • Surface characteristics:

    • Inferior surface: Smooth and concave, facing orbital contents

    • Superior surface: Convex, forming part of the anterior cranial fossa floor

  • Thickness: Thin but reinforced at sutural margins

  • Development: Pneumatization of frontal sinus may extend close to the anterior part of the orbital roof

Relations

  • Superiorly: Frontal lobes and anterior cranial fossa dura

  • Inferiorly: Orbital fat, levator palpebrae superioris, superior rectus muscle, lacrimal gland

  • Anteriorly: Frontal sinus and frontal bone

  • Posteriorly: Lesser wing of sphenoid and optic canal region

  • Medially: Ethmoid bone and cribriform plate region

  • Laterally: Zygomatic process of frontal bone and lateral orbital wall

Attachments

  • Periosteal: Orbital periosteum (periorbita) lining the inferior surface

  • Dural: Dura mater adheres to the superior surface

  • Soft tissue: Supports the lacrimal gland in the superolateral orbital roof

Function

  • Separates the orbit from the anterior cranial fossa

  • Protects orbital contents from intracranial structures

  • Supports frontal lobes superiorly

  • Provides a stable surface for orbital soft tissues and lacrimal gland

  • Maintains orbital shape and volume

MRI Appearance

T1-weighted images:

  • Bone cortex: Very low signal (black)

  • Bone marrow (diploë if present): Bright due to fatty marrow

  • Orbital fat: Bright, sharply contrasting with bone

  • Periorbita and dura: Thin low-signal lining

T2-weighted images:

  • Bone cortex: Low signal

  • Marrow: Bright, slightly less than on T1

  • Orbital soft tissues: Intermediate signal

  • CSF above orbital roof: Bright, clearly separated from bone

STIR:

  • Bone cortex: Dark

  • Marrow: Intermediate-to-dark (fat suppressed)

  • Orbital soft tissues: Intermediate

  • Useful for clear differentiation between bone and adjacent soft tissues

T1 Fat-Saturated Post-Contrast:

  • Bone cortex: No enhancement

  • Marrow: Suppressed fat signal with minimal enhancement

  • Periorbita and dura: Thin linear enhancement may be seen

  • Orbital contents: Homogeneous enhancement of soft tissues

CT Appearance

Non-Contrast CT:

  • Orbital roof: High-attenuation thin bony plate with smooth margins

  • Frontal bone component clearly visualized anteriorly

  • Lesser wing of sphenoid seen posteriorly

  • Frontal sinus air cells may be visible adjacent to anterior roof

  • Excellent delineation of bony thickness and contour

Post-Contrast CT:

  • Bone: No enhancement

  • Adjacent dura and orbital soft tissues may enhance normally

  • Clear differentiation between orbital roof and intracranial compartment

X-Ray Appearance

  • Best visualized on occipitomental (Waters) and lateral skull views

  • Appears as a thin radiopaque curved line forming the superior boundary of the orbit

  • Frontal sinus outline may overlap anterior portion

  • Smooth continuous contour without interruption in normal anatomy

MRI image

Superior wall of orbit MRI anatomy labelled image-img-00000-00000

CT image

Superior wall of orbit CT anatomy labelled image-img-00000-00000