The membrane lining the medullary cavity is the?

Endosteum membrane lines the medullary cavity.

Explanation:

The innermost central cavity of the bone is known as medullary cavity. Marrow cavity is also known as medullary cavity.

The medullary cavity composes of spongy bone and lined by the vascular membrane known as vascular membrane or endosteum. This cavity is present in any bone and holds the bone marrow and supply calcium for the bird egg shell.

Endosteum membrane

Explanation:

The membrane lining the medullary cavity is the Endosteum membrane.