This is a contiguous series of axial CT slices of the lower spine in a 28y old man. You can scan through the series either by (1) positioning the cursor over the image, holding down the left mouse button, then sliding the cursor up or down the image, or (2) hitting the keyboard keys > and < (no shift required). Scan through the series of CT slices and try to identify the lettered structures to which lines are drawn. The answers will be revealed when you click on the appropriately labelled drop-down arrows below the image.