This is a contiguous series of heart CT slices in a 42y old woman. Intravascular contrast was injected into the right median cubital vein. You can look at the video frame by frame and try to identify the lettered structures to which lines are drawn. Sometimes a structure has a line drawn to it in only one of the sections in which it can be seen; in other cases the same structure may have lines drawn to it in a few sections, not necessarily contiguous. The answers will be revealed when you click on the appropriately labelled drop-down arrows below the image.