Anatomic study of the nostril sill: classification and histologic findings

To define and investigate the normal nostril sill anatomy and classify the different forms.Photographs of the nose of 95 Korean adults and 26 preserved cadavers were studied. Classification of the different forms and cadaveric dissections and histologic studies were performed. Morphologically the noses were studied and classified into 3 types, and histologically the thickness of the soft tissue and muscle layers were measured at the nostril sill.The nostril sill was defined as the soft tissue bulge between 4 borders; medially the foot plate of the columella, laterally the ala, cephalically the vestibule, and caudally the upper lip, and classified into 3 forms. Type I: full nostril sill (55.7%), type II: point nostril sill (31.9%), and type III: flat nostril sill (12.1%). On histologic analysis, in type I, the sill consisted of fibro fatty tissue composed of a mixture of dermal collagen and gland which were thicker at the area of the sill. Also the muscle fibers beneath the sill were more protuberant in this area. The thickness of the soft tissue and muscle layers were significantly thicker at the sill area than the upper lip and vestibule. In types II and III, dermal thickening was not observed and the soft tissue thickness remained unchanged from the upper lip to the nasal vestibule. The muscle fibers showed no protuberance under the sill.This study provides references which will allow more accurate and proper correction and reconstruction of the nose and nostril sill.