Clinical anatomy of the superior labial branch of infraorbital nerve

The infraorbital nerve (ION), a branch of the maxillary division of the trigeminal nerve, provides sensory innervation to the midface via its terminal divisions. Among these, the superior labial branch (SLb) supplies the upper lip and adjacent mucosa, regions frequently involved in oral, maxillofacial, and cosmetic procedures. Despite its clinical importance, the anatomy of the SLb has received relatively limited attention compared with other ION branches. This review synthesizes current evidence on the SLb's course, branching patterns, innervation, morphometry, and variations, with emphasis on its relevance to surgical practice. Anatomical studies demonstrate that the SLb is the largest terminal division of the ION, often exhibiting medial and lateral subdivisions that anastomose with neighboring nerves. Its distribution predominantly follows a vertical orientation, supplying both cutaneous and mucosal structures of the upper lip. Variability in origin, branching, and accessory foramina underscores the need for careful surgical planning. Injury to the SLb is a recognized complication of Le Fort I osteotomy, midfacial trauma, and periapical procedures, potentially leading to long-term sensory disturbances. A comprehensive understanding of the SLb enhances intraoperative nerve preservation and may reduce postoperative morbidity, highlighting its significance for clinicians operating in the midfacial region.