1. The semilunar valves are located within the arteries that carry the blood away from the ventricles.
a. Use your scissors, blunt side within the lumen, to cut through the thick wall of the pulmonary trunk
(do not cut any other structures along the surface. Once you get to the heart, continue cutting through
the wall of the heart (much thicker) another 3-5 cm. Open up your incision to view the pockets that
line the wall of the pulmonary trunk at the junction between the heart and the trunk which make up the
pulmonary semilunar valve. As blood tries to flow back into the ventricle during ventricular
relaxation, the blood fills the pocket of the semilunar valves which prevent the blood from returning to
the heart. (See photograph of the pulmonary trunk and pulmonary semilunar valve below).
b. Observe the aortic semilunar valve by performing a similar cut through the aorta toward the left
ventricle and into the heart. Choose to make your incision along a pathway that will not damage any
other structures along the way.
c. Once you have clear access to the aortic semilunar valve, you will find two openings within the
pockets of the valve. These are the coronary ostea. The coronary ostea are the openings that
deliver blood into the coronary arteries that serve the cardiac tissue of the myocardium. Place your
probe into one of the ostea and view the external anterior surface—as you gently wiggle the probe,
you should be able to identify a coronary artery that passes beneath one of the atria or along the
interventricular sulcus