\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.
Note: The term is also often applied to the thin, expanded
      parts, of various texture, both in animals and
      vegetables.
{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.