pericardium

The membranous sac filled with serous fluid that encloses the heart and the roots of the aorta and other large blood vessels.

In anatomy and zoology: A somewhat conically shaped membranous sac, inclosing the heart and the origin of the great vessels.

A blood-sinus or special cavity beneath the carapace of a crustacean, in which the heart is suspended by ligaments and arteries, but not otherwise connected.

In mollusks, the spacious dorsal cœlom or body-cavity which is traversed by the contractile vessel which acts like a heart.

The double baglike fold of serous membrane which incloses the heart.

A serous membrane that surrounds the heart allowing it to contract.

a serous membrane with two layers that surrounds the heart