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Topic

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Infraorbital foramen

The infraorbital foramen is an opening on the anterior surface of the maxilla, located inferior to the infraorbital margin. It represents the terminal opening of the infraorbital canal, transmitting the infraorbital nerve and vessels from the orbit to the face.

It is an important anatomical landmark in maxillofacial surgery, dental anesthesia, and facial trauma, providing sensory innervation to the lower eyelid, lateral nose, upper lip, and cheek. Its position is typically aligned with the mid-pupillary line and lies approximately 6–10 mm below the infraorbital rim.

Synonyms

  • Infraorbital opening
  • Infraorbital canal exit
  • Maxillary infraorbital aperture

Location and Structure

  • Position: On the anterior maxilla, inferior to the infraorbital margin
  • Shape: Oval or round opening
  • Orientation: Opens anteriorly and slightly inferiorly
  • Continuation: Distal opening of the infraorbital canal
  • Surface relation: Lies above the canine fossa and anterior wall of the maxillary sinus

Relations

  • Superiorly: Infraorbital margin and orbital floor
  • Inferiorly: Maxillary alveolar process and upper teeth roots
  • Medially: Nasal aperture and maxillary sinus wall
  • Laterally: Zygomatic process of the maxilla
  • Posteriorly: Infraorbital canal within maxilla

Contents

  • Infraorbital nerve (branch of maxillary division of trigeminal nerve, V2)
  • Infraorbital artery (branch of maxillary artery)
  • Infraorbital vein

Function

  • Provides passage for neurovascular structures from orbit to face
  • Enables sensory innervation of midface region
  • Serves as a key landmark for infraorbital nerve block anesthesia
  • Important surgical reference point in orbital and maxillary procedures

MRI Appearance

T1-weighted images:

  • Bone cortex: Low signal (dark)
  • Marrow of maxilla: Bright signal due to fatty marrow
  • Infraorbital canal/foramen: Seen as a small linear or round low-signal opening within the maxilla
  • Neurovascular bundle: May appear as small intermediate signal structure within canal

T2-weighted images:

  • Cortex: Dark
  • Marrow: Bright, slightly less intense than on T1
  • Foramen: Hypointense opening with surrounding hyperintense marrow
  • Soft tissues: Intermediate-to-bright signal

STIR:

  • Normal marrow: Intermediate-to-dark signal
  • Foramen: Dark focal interruption in maxillary bone
  • Surrounding soft tissue: Suppressed fat signal with clearer delineation of canal contents

CT Appearance

Non-Contrast CT:

  • Bone cortex: High attenuation, sharply defined
  • Foramen: Well-defined round or oval lucency on anterior maxilla
  • Infraorbital canal: Linear channel extending posteriorly toward orbital floor
  • Best modality for precise localization and morphologic evaluation

Post-Contrast CT:

  • Bone: No enhancement
  • Neurovascular contents: Subtle enhancement within canal

MRI images

Infraorbital foramen mri axial image 1

MRI images

Infraorbital foramen mri axial image