Branching patterns of the infraorbital nerve and topography within the infraorbital space.

The infraorbital nerve (ION) is the terminal branch of the maxillary nerve; it supplies the skin and mucous membranes of the middle portion of the face. This nerve is vulnerable to injury during surgical procedures of the middle face. Severe pain and loss of sense are noted in patients whose infraorbital nerve is damaged. In the study presented here, we investigated the branching pattern and topography of the ION, about which little is currently known, by dissecting 43 hemifaces of Korean cadavers. In most cases, the infraorbital artery was located in the middle (73.8%) and superficial to the ION bundle (73.8%) at its exit from the infraorbital canal. The ION produced four main branches, the inferior palpebral, internal nasal, external nasal, and superior labial branches. The superior labial branch was the largest branch of the ION produced the most sub-branches. These sub-branches were divided into the medial and lateral branches depending upon the area that they supplied. We were able to classify four types of branching pattern of the external and internal nasal branch and the medial and lateral sub-branches of the superior labial branch of the ION at the site of their emergence through the infraorbital foramen (types I-IV). Type I, where all four branches are separated occurred the most frequently (42.1%). These findings will help to preserve the ION while performing certain types of maxillofacial surgery, such as removal of a tumor from the upper jaw and fracture of the upper jaw.