In chapter 17 you learned about the big picture of circulation through the pulmonary and systemic routes, and how the right and left heart function in those routes. You also learned that systemic routes go to all of the organs/tissues in the body. One of those organs is the heart wall muscle (myocardium). Route blood from inside the right atrium (the start of the pulmonary circuit) to the coronary sinus (the end of the systemic circuit that serves heart wall tissue). Your route must include all heart chambers and valves..