Adventitious membrane

Membrane Mem"brane, n. [F., fr. L. membrana the skin that covers the separate members of the body, fr. L. membrum. See {Member}.] (Anat.) A thin layer or fold of tissue, usually supported by a fibrous network, serving to cover or line some part or organ, and often secreting or absorbing certain fluids. [1913 Webster]

Note: The term is also often applied to the thin, expanded parts, of various texture, both in animals and vegetables. [1913 Webster]

{Adventitious membrane}, a membrane connecting parts not usually connected, or of a different texture from the ordinary connection; as, the membrane of a cicatrix.

{Jacob's membrane}. See under {Retina}.

{Mucous membranes} (Anat.), the membranes lining passages and cavities which communicate with the exterior, as well as ducts and receptacles of secretion, and habitually secreting mucus.

{Schneiderian membrane}. (Anat.) See {Schneiderian}.

{Serous membranes} (Anat.), the membranes, like the peritoneum and pleura, which line, or lie in, cavities having no obvious outlet, and secrete a serous fluid. [1913 Webster]