NaRes

Nares are the two external openings of the nose, commonly referred to as the nostrils. The singular form is naris and the plural is nares. They mark the entry to the nasal cavities and are separated by the nasal septum on the midline.

Each naris is bordered laterally by the alae nasi, the flaring cartilaginous and skin folds, and medially by the nasal septum. The rim of the naris forms the margin of the nasal vestibule, which is lined with skin containing sebaceous glands and coarse hairs known as vibrissae. The vestibule transitions to the internal nasal cavity, which is lined by mucous membrane and rich in glands.

The nares connect to the nasal cavity through the nasal vestibule; the posterior openings of the nasal cavity are the internal nares, also called the choanae, which lead to the nasopharynx. This arrangement allows airflow to enter the nasal passages where it is filtered, warmed, and humidified before reaching the lungs. The nasal mucosa contains mucus-producing cells and cilia that trap particles and help move mucus toward the pharynx.

Functionally, the nares enable breathing, contribute to olfaction by providing access to odorants, and participate in conditioning inspired air. Hair and mucous membranes filter particles, while the mucosa warm and humidify the air to protect the lower respiratory tract. Clinically, obstruction, trauma, or congenital anomalies affecting the nares can impair patency and breathing. Etymologically, naris is Latin for nostril; nares is the plural form.