The only neurovascular structure of any significance that must be negotiated with procedures in the midfacial region is the infraorbital neurovascular bundle. The infraorbital nerve is the largest cutaneous branch of the maxillary division of the trigeminal nerve. The artery and vein that accompany the infraorbital nerve are surgically insignificant. The nerve exits the infraorbital foramen, 7 to 10 mm inferior to the infraorbital rim just medial to the zygomaticomaxillary suture, or approximately at the medial and middle thirds of the orbit. The infraorbital nerve divides after exiting the infraorbital foramen into terminal branches that spread fanwise from into the lower eyelid; the nasal branches supply the skin on the lateral surface of the lower half of the nose. Three of the four superior labial branches enter the lip between its muscles and the mucous membrane. These nerves supply not only the mucous membrane of the upper lip, but also its skin, which they reach by perforating the orbicularis oris muscle. Damage to this nerve results in loss of sensation to these areas, and possibly dysesthesia.
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