So this layer, the epicardium, is actually physically attached. It's fused with our visceral layer of the inner pericardium. So this visceral layer of the inner pericardium is attached to the epicardium, this layer of the heart. And together these two layers play a role in lubricating our heart along with the fluid found within the pericardial cavity. Now, the thickest segment of the heart is the myocardium and this is the middle portion. This consists of specialized heart cells known as myocytes, also known as cardiac muscle cells.