Posterior Dilator Naris Muscle

Description

Arising from the maxilla in the region of the canine fossa, the posterior dilator naris (dilator naris posterior) courses superiorly and anteriorly to insert into the alar cartilage and adjacent skin of the ala nasi. Its fibers sit lateral to the nasal vestibule and just inferior to the upper lateral cartilage, blending at the alar base with neighboring slips of the nasalis and the levator labii superioris alaeque nasi. Medially, the muscle relates to the margin of the naris and the fibroareolar tissue around the external nasal valve. Small, superficial muscle. Functionally, this slip influences the contour and patency of the external nasal valve, the narrowest segment of the nasal airway for many patients. It matters in rhinoplasty and nasal valve surgery because maneuvers that alter alar cartilage position, alar base width, or soft-tissue tension can unintentionally change nasal airflow, and subtle asymmetries in the alar rim often reflect differences in perinasal mimetic musculature. Denervation or scarring after alar base reduction, cleft-related nasal repair, or facial nerve injury can reduce dynamic flare and contribute to exercise-related obstruction. Use this illustration in head and neck anatomy teaching to anchor discussions of the muscles of facial expression around the nose, their attachments to cartilage and skin, and how they differ from true sphincteric action at the naris. It also suits operative atlases and patient-education materials describing external nasal valve collapse, alar rim retraction, and surgical planning for alar base procedures in male nasal anatomy. Anatomical accuracy verified by SciePro's Medical Advisory Board.