Nose

The facial structure that serves as the organ of smell as well as the portal through which air enters and leaves the pulmonary system. Air enters the nose through the nostrils, passing beneath the olfactory NERVE endings. Odor molecules activate the nerve endings, which convert the stimulation into nerve signals the olfactory nerve (first cranial nerve) transmit to the BRAIN. The air then swirls through the paranasal SINUSES, cavities within the bones that form the face. The sinuses warm and moisturize the air, bringing it closer to the temperature and humidity of the inner airways. Because it extends from the face, the nose is vulnerable to traumatic injury and also to environmental exposure hazards such as FROSTBITE and SUNBURN. Numerous dermatological conditions can affect the outer nose, among them ACNE, ROSACEA, SKIN CANCER, ACTINIC KERATOSIS, and KERATOACANTHOMA. Surgery to alter the appearance of the nose, RHINOPLASTY, is one of the most common cosmetic procedures that plastic surgeons perform.