Levator Anguli Oris Beneath The Skin, Lateral View

Description

Running superior to the angle of the mouth, the levator anguli oris (also termed the quadratus labii superioris in older nomenclature) is presented in lateral profile beneath reflected facial skin. Its fibers arise from the canine fossa of the maxilla, inferior to the infraorbital foramen, then descend inferomedially to blend at the modiolus with the orbicularis oris, zygomaticus major, and depressor anguli oris. Superficial to it lie the risorius and zygomaticus muscles, while the maxillary alveolar process, teeth, and adjacent nasal cavity provide the bony context anteriorly. Masseter and temporalis bulk the posterior cheek and temporal fossa, with sternocleidomastoid forming the prominent lateral neck column. Depression and elevation at the oral commissure are often taught as simple opposites, but this muscle’s deep position makes its contribution easy to miss unless you track its course from the maxilla into the modiolus. It matters in facial nerve anatomy: the zygomatic and buccal branches course in the superficial musculoaponeurotic system (SMAS) plane over the midface, so surgical dissection for facelift, midface lift, or repair of cheek lacerations must respect the layered relationship between skin, SMAS, and deeper mimetic muscles. Small asymmetries at the mouth corner after Bell palsy or iatrogenic nerve injury often reflect loss of coordinated action among levator anguli oris, zygomaticus major, and orbicularis oris. Plastic surgery texts, dental and maxillofacial teaching modules, and head and neck anatomy courses can use this lateral, under-skin view to orient learners to the modiolus as a convergence point and to relate facial expression muscles to maxillary landmarks like the infraorbital region. A good plate for correlating with cosmetic injection planning around the nasolabial fold and perioral region. Anatomical accuracy verified by SciePro's Medical Advisory Board.