Posterior Dilator Naris

Description

Arising from the lateral nasal cartilages and adjacent maxilla, the posterior dilator naris fibers blend with the nasalis and course toward the ala nasi along the rim of the naris, positioned superficial to the nasal aperture and anterior to the nasal cavity. From the lateral perspective, the muscle sits inferior to the nasal bone and superior to the upper lip musculature, with its fine slips fanning anteroinferiorly along the alar margin. Nearby bony landmarks, including the maxilla, nasal bone, and the anterior contour of the mandible and dentition, provide orientation. The auricle and cervical vertebrae remain in the posterior field as reference anatomy. Clinically, isolating the posterior dilator naris matters because it is one of the small mimetic muscles that modulates external nasal valve caliber, the region where the ala and lateral wall can collapse during inspiration. Surgeons addressing nasal obstruction, particularly external nasal valve collapse after rhinoplasty or trauma, use these fiber directions to anticipate functional changes when modifying the lateral crus, placing alar batten grafts, or working in the alar base. Small muscle. Real airflow consequences. Teaching and publication use cases include head and neck anatomy labs focused on muscles of facial expression, ENT and facial plastic surgery texts covering nasal valve mechanics, and patient education materials that explain why alar rim support or scar tethering can change nostril shape and breathing on the lateral view. It also fits well in board-style review content that contrasts the nasalis (compressor naris) with dilator components during sniffing and flaring. Anatomical accuracy verified by SciePro's Medical Advisory Board.