The pericardium is a tough fibroelastic sac which covers the heart from all sides except at the cardiac root (where the great vessels join the heart) and the bottom (where only the serous pericardium exists to cover the upper surface of the central tendon of diaphragm).

This creates a pouch-like potential space around the heart enclosed between the two opposing serosal surfaces, known as the pericardial space or pericardial cavity, which is filled with a small amount of serous fluid to lubricate the heart's movements and cushions it from any external jerk or shock.

[9] The pericardium sets the heart in mediastinum and limits its motion, protects it from infection, lubricates it and prevents excessive dilation in cases of acute volume overload.

This condition typically causes chest pain that spreads to the back and is made worse by lying flat.

In patients suffering with pericarditis, a pericardial friction rub can often be heard when listening to the heart with a stethoscope.

Pericardial effusions often occur secondary to pericarditis, kidney failure, or tumours and frequently do not cause any symptoms.

Fluid can be removed from the pericardial space for diagnosis or to relieve tamponade using a syringe in a procedure called pericardiocentesis.

Another feature is the sharp delineation of pulmonary artery and transverse aorta due to lung deposition between these two structures.