The pericardium envelops the heart and attaches to the roots of the great vessels. This includes the ascending aorta, pulmonary artery, pulmonary veins, the last 2–4 cm of superior vena cava, and inferior vena cava.

The phrenic nerves descend on the lateral surfaces of the pericardium.

Acute accumulation of as little as 200 mL of fluid in the pericardial sac may result in fatal cardiac tamponade.

The right atrium is paper thin, approximately 2 mm. The left atrium is slightly thicker at approximately 3 mm.

The right ventricle is approximately 4 mm thick and the left ventricular wall thickness is approximately 12 mm.

The two main coronary arteries, left main and right coronary arteries, originate at the root of the aorta, as it exits the left ventricle. The left main coronary artery divides into the left anterior descending artery (LAD) and the circumflex artery, and provides blood supply to the left heart. The right coronary artery divides into the right posterior descending and acute marginal arteries, supplying blood to the right heart, as well as the sinoatrial and atrioventricular nodes responsible for regulating cardiac rhythm.