Nasal cavity. Three-dimensional computed tomo- graphy (CT) scan of the nasal cavity. At upper left (and partially obscured at upper right), part of the ridge-like conchae can be seen. These are a group of three plates which are covered in nerves responsible for the sense of smell. The nasal cavity is lined with a mucous membrane which warms, moistens and filters the air, and prevents airborne particles and microorganisms entering the lungs. CT scans use X-rays to create slice images through the body, which can be combined to give this 3-D endoscopic view. This virtual endoscopy allows study of the body's internal structures without using invasive techniques.