Healthy heart. Coloured three-dimensional computed tomography (CT) chest scan revealing a healthy heart (orange, lower centre) in the ribcage (pink). Above the heart are the ascending (pink & orange) and descending (blue) aorta, as well as the pulmonary artery (purple) and the oesophagus (olive, upper left). The heart is a hollow muscle which pumps deoxygenated blood to the lungs through the pulmonary artery and oxygenated blood to the body through the aorta. Food travels down the oesophagus to the stomach. CT scans use X-rays to form slice" images of the body. These are built into a three-dimensional image by computer."