Orbicularis Oris Muscle Beneath the Dermal Layer, Anterior View

Description

Seen from the front with the dermal layer removed, the orbicularis oris forms a continuous circular muscle around the oral fissure, with superficial fibers blending laterally into the modiolus at the angle of the mouth. Superiorly and inferiorly, its fibers interdigitate with the elevators and depressors of the lips, including levator labii superioris and depressor labii inferioris, while the buccinator contributes deeper fibers at the oral commissure. The upper and lower lips (labia) frame the stoma, and adjacent mimetic muscles around the nasal ala and chin sit immediately superior and inferior to the sphincter ring. Anterior facial topography remains evident. Functionally, this is the key sphincter of the mouth, driving lip seal, puckering, and articulation, and it matters when you are mapping perioral motion rather than simply memorizing a facial muscle list. Injuries to the marginal mandibular branch of the facial nerve during submandibular or neck procedures can produce lower lip asymmetry by denervating depressor muscles, but preserved orbicularis oris tone can mask deficits unless the commissure and lip competence are assessed carefully. In cleft lip repair and revision, surgical planning often hinges on restoring orbicularis oris continuity across the philtral region and reconstituting the modiolus. Use this anterior facial anatomy illustration for head and neck anatomy teaching, plastic and reconstructive surgery texts, and speech and swallowing coursework where perioral sphincter mechanics need clear visuals. It also suits patient-facing education on facial nerve palsy, lip competence, and outcomes after cheiloplasty. Anatomical accuracy verified by SciePro's Medical Advisory Board.