Risorius Muscle Under the Skin, Anterior View

Description

Positioned in the superficial cheek, the risorius is shown as a thin, variably developed band coursing from the parotid and masseteric fascia toward the modiolus at the lateral angle of the mouth. Medial to it sit the orbicularis oris and depressor anguli oris around the oral commissure, while the zygomaticus major and minor lie superior and oblique, descending from the zygomatic bone toward the upper lip and modiolus. Laterally, the risorius crosses the masseter region in the plane where the buccal branches of the facial nerve and the parotid duct typically travel. Fiber direction is clear. So are the facial landmarks. Tracing the risorius in an anterior, subcutaneous view matters because it clarifies how a small muscle can still influence smile dynamics by retracting the angle of the mouth laterally, often acting in concert with zygomaticus major rather than elevating the commissure itself. That distinction comes up in facial reanimation planning and in analyzing asymmetric smiles after buccal branch facial nerve injury, where the modiolus becomes a functional crossroads for multiple perioral muscles. The same topography helps when teaching injection technique for platysmal bands, DAO hyperactivity, or perioral rhytids, since diffusion into adjacent elevators or retractors can visibly change oral commissure position. Facial anatomy and head and neck courses can use this plate to teach muscles of facial expression by layer, with the modiolus as the organizing landmark for perioral vectors. Plastic surgery, ENT, and oral and maxillofacial publications often need a clean depiction of risorius relationships when discussing facelift dissection planes, parotid duct protection, or targeted chemodenervation around the smile complex. Anatomical accuracy verified by SciePro's Medical Advisory Board.