Depressor Anguli Oris Muscle Beneath the Dermal Layer, Anterior View

Description

Superficial to the lower face, the dermal layer is rendered translucent to expose the paired depressor anguli oris muscles as triangular slips descending from the modiolus at the oral commissure to their broad mandibular origin along the oblique line. Fibers run inferolaterally from the corner of the mouth, lying lateral to depressor labii inferioris and blending superiorly with orbicularis oris at the angle. The mentolabial region and mandibular body form the bony frame inferiorly. Symmetry is emphasized. Functionally, depressor anguli oris pulls the mouth corner inferiorly and slightly laterally, contributing to frowning and to the downturned commissure seen with aging, perioral volume loss, or hypertonicity. This anterior, subdermal presentation helps clarify why botulinum toxin placed too medially can weaken adjacent depressor labii inferioris and produce lower-lip asymmetry, while overly lateral injection risks diffusion toward risorius and an unnatural smile line. Small muscle, big aesthetic consequences. The relationship to the modiolus also makes it a useful landmark when discussing perioral reconstruction and vector planning for commissuroplasty. Use this asset in head and neck anatomy teaching for facial expression, dental and maxillofacial modules on perioral musculature, or aesthetic medicine content covering DAO chemodenervation and lower-face rejuvenation. It also fits surgical atlases and patient-education materials explaining frown mechanics and asymmetry at the oral commissure. Anatomical accuracy verified by SciePro's Medical Advisory Board.