This page contains photos of the sheep heart dissection. All the major vessels are represented, many are labeled with colored pencils so that you can see exactly where each is located. The heart can be confusing because it is not perfectly symmetrical. Students often confuse the left and the right side of the heart. One easy way to reference is to note that the left side of the heart is the more muscular part, it is where blood is pushed out (from the left ventricle) into the aorta where it will deliver oxygenated blood to the entire body. Blood returning to the heart goes to the right atrium via the superior and inferior vena cava. The right side is not as muscular because it only needs to pump that blood to the lungs (via pulmonary artery) and then get the blood back to the left atrium (via pulmonary vein). This type of circulation is called a DOUBLE LOOP.