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Orbital surface of maxilla

The orbital surface of the maxilla forms the major part of the floor of the orbit, contributing to the support and contour of the orbital cavity. It is a thin, concave bony plate that articulates with the zygomatic, palatine, and lacrimal bones, and forms the inferior boundary of the orbital cavity, separating the orbit from the maxillary sinus below. The surface contains the infraorbital groove and canal, which transmit the infraorbital nerve and vessels, and may show natural foramina for neurovascular structures. Variations in thickness and contour are common, and this area is clinically significant because its thinness makes it susceptible to blowout fractures.

Synonyms

  • Maxillary orbital floor

  • Orbital plate of maxilla

  • Inferior orbital surface of maxilla

Function

  • Forms the floor of the orbit, providing structural support to the globe

  • Separates the orbital cavity from the maxillary sinus

  • Transmits the infraorbital nerve and vessels through the infraorbital canal

  • Serves as a key surgical landmark in orbital and midface procedures

MRI Appearance
T1-weighted images:

  • The orbital surface of the maxilla appears as a thin hypointense bony line, bordering the orbit

  • Surrounding orbital fat appears hyperintense, providing excellent contrast

  • Infraorbital canal may be faintly visible as a small tubular hypointense structure

  • Pathological changes such as fractures or bone lesions appear as disruption of the hypointense line

T2-weighted images:

  • Bony plate remains hypointense, while orbital fat is hyperintense

  • Edema or hematoma from trauma may appear hyperintense, highlighting orbital floor fractures or sinus involvement

STIR (Short Tau Inversion Recovery):

  • Fat suppression enhances visualization of bone marrow edema or soft tissue pathology

  • Normal orbital floor remains hypointense, while fractures or inflammatory changes appear hyperintense

CT Appearance

  • The orbital surface appears as a thin, hyperdense bony plate forming the orbital floor

  • Clearly delineates the infraorbital groove and canal

  • The surrounding air of the maxillary sinus appears hypodense, creating natural contrast

  • CT is ideal for evaluating blowout fractures, orbital floor defects, bony erosions, and surgical planning

  • Variations in thickness and contour can be accurately assessed in axial, coronal, and sagittal planes

MRI images

Orbital surface of maxilla mri axial image -img-00000-00000