<prompt> Structure passing through the opening marked 3 in the diaphragm isOesophagusLeft gastric nerveRight phrenic nerveHemiazygos vein  <response>: Caval opening T8- The caval opening passes through the central tendon of the diaphragm. It contains the inferior vena cava and the right phrenic nerve. Ref anatomy B. D. Chourasia thorax p54 