Human heart, 3D coloured computed tomography (CT) scan. This is an anterior (frontal) view. The heart is a hollow muscular organ that receives and pumps blood from and around the body through the veins and arteries that branch out from its four internal chambers. The external surface of the heart includes the coronary arteries and veins that supply blood to the heart muscle. This scan includes parts of the heart's major veins and arteries.