Lateral Perspective of the Depressor Anguli Oris Muscle Under the Skin

Description

Arising from the oblique line of the mandible, the depressor anguli oris is shown as a triangular slip in the inferolateral perioral region, running superiorly and medially to blend into the modiolus at the corner of the mouth. Laterally, its fibers sit adjacent to the anterior border of the masseter and the lower portion of the buccinator, while medially it approaches the depressor labii inferioris and the orbicularis oris. Superficial integument remains intact, so the muscle reads as a subcutaneous plane rather than a deep dissection. Key surface neighbors, including the zygomaticus major superiorly and the sternocleidomastoid posteriorly in the neck, provide orientation in this lateral head view. Functionally, this muscle pulls the labial commissure inferiorly and slightly laterally, opposing the elevator group during facial expression. Weakness or denervation after injury to the marginal mandibular branch of the facial nerve (CN VII), a known risk in submandibular incision placement and parotid surgery, produces an asymmetric smile with drooping of the oral angle. Small muscle. Big visual consequence. This artwork fits well in head and neck anatomy teaching, facial expression modules, and procedural education where clinicians need to correlate surface landmarks with the subcutaneous mimetic musculature, including botulinum toxin planning for downturned mouth corners and reconstructive discussions after facial nerve palsy. It also supports figure plates for ENT, oral and maxillofacial surgery, and dermatologic surgery texts that describe the modiolus and perioral muscle balance. Anatomical accuracy verified by SciePro's Medical Advisory Board.