MEMBRANE, (in Anatomy,) Gr. ; Lat. Membrana ; Fr. 114embrane ; Germ. die Haut. This term is commonly applied to designate those textures of the body which are disposed or arranged as laminae, destined to cover organs, to line the interior of cavities, or either singly or by their application one over the other, to constitute the walls of canals or tubes. Expansion with very slight thickness is the main morphological characteristic of mem branes in their ordinary sense.
I do not intend here to give any classifica tion of the membranes : the term is extensively used in descriptive as well as in general ana tomy ; and anatomists differ materially as to the degrees within which they limit its meaning. Anatomists hitherto have been content to adopt the gross anatomy of the textures as the basis of their classification, a circumstance which has given rise to much error, as well as to great variety of opinion. Now, aided as we are by excellent microscopes, and by the light which they have thrown upon the minute anatomy of the tissues, we should only admit that classifi cation which is based on an ultimate or even proximate anatomical analysis. As these points
will be all fully treated of in the article Tissu E, reference is made to it for the details respecting the membranes.
(R. B. Todd.) MENINGES.—This word signifies mem branes; it is specifically applied to those mem branous expansions which cover and more or less protect the brain and spinal cord, and in this sense is best interpreted by the German word Hirnhaut. The term is in common use on the continent, but not so frequently em ployed by British anatomists, although always understood by them in the sense above given. It appears to have been thus applied first by Galen, who distinguished 1.4,37 zrazuTipn, or the dura mater, and fonty4 orrn, or the pia mater.
The description of the membranes of the brain and spinal cord will be found in the article NERVOUS CENTRES.
(R. B. Todd.)