Which organ is enclosed in the pericardium?

Your pericardium is a protective, fluid-filled sac that surrounds your heart and helps it function properly. Your pericardium also covers the roots of your major blood vessels as they extend from your heart. These are known as your “great vessels,” and they include your aorta, main pulmonary artery, pulmonary veins, and superior and inferior vena cava. Your pericardium is located in your chest, where it surrounds your heart. Your heart is located in the front of your chest, slightly to the left of your breastbone (sternum). If you have dextrocardia, your heart is slightly to the right of your breastbone.

Source: Cleveland Clinic