Human heart. Historical artwork of several aspects of the interior and exterior of the human heart. The main body of the heart is a hollow, muscular sac comprising two atria and two ventricles. At the top of the heart are various blood vessels by which blood enters and leaves the heart. The atria and ventricles contract to force blood out of the heart in the aorta and pulmonary artery. The heart muscle is supplied with blood by coronary arteries, which branch across its surface. This artwork is by Alexander Ramsey (1754-1824) and was published in Anatomy of the Heart, Cranium and Brain in Edinburgh in 1813.