a: the part of the face that bears the nostrils and covers the anterior part of the nasal cavity; broadly: this part together with the nasal cavity b: the anterior part of the head above or projecting beyond the muzzle
Prominent structure between and below the eyes. With the complex nasal cavity behind it, it functions for breathing and smelling. Behind the front section (vestibule), which includes the nostrils, it is divided vertically by three convoluted ridges (conchae) into air passages. In the highest one, the olfactory region, a small segment of mucous membrane lining contains neurons covered by a moisture layer, in which microscopic particles in inhaled air dissolve and stimulate the neurons. The rest of the cavity warms and moistens inhaled air and filters particles and bacteria out of it. Sinus cavities in the bone on both sides of the nose drain into the air passages. During swallowing, the soft palate closes off the back of the nose against food.