What is the protective covering of the heart and lungs called?

The protective covering of the heart and lungs is known as the pericardium. The pericardium is a double-walled sac that contains the heart and the roots of the great vessels. It plays a crucial role in protecting the heart while also allowing it to function efficiently within the thoracic cavity.

The thorax refers to the entire chest area that houses the heart, lungs, and other vital organs, but it does not specifically denote the protective covering. The diaphragm is a muscular structure that separates the thoracic cavity from the abdominal cavity, aiding in respiration but not serving as a covering. The term cavity generally describes the space within an organ or body, without specifying a protective function. Thus, the pericardium is the precise term that describes the specific protective covering for the heart.