The pericardial space is the cavity between which layers of the pericardium, and it contains serous fluid?

• A. Between visceral and parietal layers, containing serous fluid
• B. Between endocardium and epicardium, containing blood
• C. Between atria and ventricles, containing air
• D. Within the myocardium, containing lymph

Answer: (A)

The pericardial cavity is the space between the two layers of the pericardium—the visceral layer that adheres to the heart and the parietal layer that lines the fibrous pericardium. This potential space normally contains a small amount of serous fluid, which lubricates the heart as it moves, reducing friction with each beat.

The other options describe spaces or contents that aren’t the pericardial cavity: endocardium and epicardium are layers of the heart wall themselves, not separate pericardial layers with a fluid-filled space; the gap between atria and ventricles is the chambers/valves of the heart, not a fluid-filled cavity; and the myocardium is the thick muscular layer of the heart wall, not a space containing lymph.