naris

Naris is the anatomical term for each external opening of the nasal cavity, commonly referred to as a nostril. The pair are the nostrils; the singular naris and plural nares. Each naris opens into the nasal vestibule and is bounded laterally by the ala of the nose and medially by the nasal septum. The rims form part of the nasal valve, a key determinant of airflow resistance. The vestibule is lined with skin bearing coarse hair (vibrissae) that helps filter large particles; deeper mucosa consists of respiratory epithelium supported by cartilage and bone.

Functionally, the naris serves as the entryway for air into the nasal cavity, where it is filtered, warmed, and humidified before moving to the lungs. Airflow through each naris can be asymmetrical and is subject to the nasal cycle, a periodic switching of airflow between sides driven by autonomic regulation of turbinates and mucosa. Olfactory receptors are located more posteriorly in the nasal cavity, but airflow through the nares is essential for scent detection as well as respiration.

Clinical relevance includes variation in naris size or patency due to congenital factors, trauma, or inflammation. Obstruction of one or both nares can cause nasal congestion and breathing difficulties, particularly in infants. Deviated septum, nasal valve collapse, polyps, or edema can reduce narial airflow and influence overall nasal function. Procedures such as septoplasty, rhinoplasty, or alar plasty may address narial patency and aesthetics, depending on the underlying cause.

Terminology: naris is Latin for nostril; nares is the plural form. In medical literature, nares is typically used to refer collectively to both openings.