Lateral Presentation of the Labial Commissure of a Male Head

Description

Seen in lateral profile, the labial commissure marks the junction where the superior and inferior lips meet at the mouth corner in an adult male. The upper lip (labium superius) lies superior to the lower lip (labium inferius), and both converge laterally at the oral rima, with the vermilion border transitioning posteriorly into the oral mucosa. Immediately deep to the commissure sits the modiolus, a fibromuscular node where orbicularis oris interlaces with the buccinator and the elevators and depressors of the angle of the mouth (including zygomaticus major, levator anguli oris, depressor anguli oris, and risorius), organizing the lateral contour of the oral region. Clinically, this corner of the mouth matters because small positional changes reflect dysfunction of the facial nerve branches controlling perioral muscles, a routine focus in Bell palsy assessment and postoperative facial reanimation follow-up. Angular cheilitis localizes to the labial commissure and often tracks with saliva pooling, denture-related changes in vertical dimension, or iron and B vitamin deficiency, so a clear lateral view helps correlate surface findings with the underlying modiolus. Surgeons also reference this landmark when planning cleft lip repair markings, commissuroplasty, or excision and reconstruction of lesions at the oral commissure where scar contracture can restrict oral aperture. Use this illustration in head and neck anatomy teaching, facial expression modules in dental and medical curricula, and clinical education materials on perioral dermatology and facial nerve examination. It also suits surgical atlases and patient-facing consent documents for commissure-adjacent procedures where lateral alignment of the mouth corner must be communicated plainly. Anatomical accuracy verified by SciePro's Medical Advisory Board.