Anatomical Location
The foramen is located on the anterior surface of the maxilla body (corpus maxillae), which features a concave contour.
- Topography: Situated inferior to the infraorbital margin (margo infraorbitalis), which separates the anterior surface of the maxilla from its orbital surface.
- Canine Fossa: Inferior to the foramen lies a shallow depression known as the canine fossa (fossa canina).
- Connection to the Orbit: The foramen is the terminal opening of the infraorbital canal (canalis infraorbitalis). The canal begins at the infraorbital sulcus (sulcus infraorbitalis) on the orbital floor; the infraorbital nerve enters via the inferior orbital fissure, traverses the orbit, sulcus, and canal.
Contents
The structures emerging through the foramen onto the face include:
- Infraorbital nerve (n. infraorbitalis) — the direct continuation of the maxillary nerve (CN V2). Upon exiting the foramen, it divides into terminal branches; the superior labial branches form the minor goose's foot (pes anserinus minor).
- Infraorbital vessels — the infraorbital artery (a. infraorbitalis) and infraorbital vein (v. infraorbitalis).
Innervation Zones
The terminal branches of the infraorbital nerve supply:
- Skin and mucosa of the upper lip.
- Lower eyelid.
- Infraorbital region.
- Nasal ala (wings of the nose).
- Skin of the nasal septum.
Note: The middle and anterior superior alveolar branches branch off the infraorbital nerve within the infraorbital canal and, along with the posterior superior alveolar nerves, form the superior dental plexus.
Clinical Significance: Anesthesia
The infraorbital foramen serves as a key anatomical landmark for extraoral infraorbital nerve block. This local anesthesia technique blocks the anterior and middle superior alveolar nerves.
- Technique: The clinician palpates the foramen's projection on the skin and firmly presses the overlying soft tissues against the bone to prevent accidental globe injury and to stabilize the needle entry. The needle is inserted 1 cm inferior and medial to the foramen projection, then advanced superiorly, posteriorly, and laterally toward the infraorbital foramen until bone is contacted. A local anesthetic depot of 0.5–1 mL is deposited near the foramen before locating the canal entrance. A characteristic 'drop' sensation or patient pain reaction indicates entry.
- Complications: Potential complications include vascular injury resulting in hematoma, and transient skin ischemia in the infraorbital region. Rare complications due to poor technique include diplopia and traumatic neuritis of the infraorbital nerve.
Clinical Significance: Surgery and Trauma
- Maxillary Sinus Surgery: During surgical approaches for odontogenic maxillary sinusitis, trephination of the anterior maxillary sinus wall is performed within the canine fossa. It is critical to avoid injuring the neurovascular bundle exiting the infraorbital foramen to prevent hemorrhage and postoperative sensory deficits.
- Facial Trauma: In Le Fort II midface fractures, the fracture line frequently runs through the infraorbital canal and foramen, resulting in infraorbital nerve entrapment or transection.
- Neurology: Congenital or acquired narrowing of neural canals at trigeminal nerve exit points, including the infraorbital foramen, can contribute to peripheral neuralgia.