The double layer outermost membrane around heart containing fluid is: Group of answer choicespericardiummyocardiumendocardiumseptum

The double layer outermost membrane around the heart containing fluid is known as the pericardium.

Explanation:

The pericardium is a thin, sac-like structure that envelops the heart and consists of two layers, the fibrous pericardium (outer layer) and the serous pericardium (inner layer). The serous layer further divides into the parietal layer and the visceral layer (epicardium), creating a space known as the pericardial cavity filled with pericardial fluid. This fluid serves several important functions, including lubricating the heart to reduce friction during heartbeats and providing a cushion against physical shocks.

In contrast:

• The myocardium is the muscular tissue of the heart responsible for its contractions.
• The endocardium is the inner lining of the heart chambers.
• The septum is a wall dividing the left and right sides of the heart.

Thus, the correct answer from the provided choices is pericardium.