(From Mesenterium 4944 the middle, and intestine,) e/iichordis; mesaraeon; the mesentery, thus named from its being' in the middle of the intestines, is a duplicature of the peritonaeum, nearly of a circular figure fixed in the middle of the abdomen, connected by a cellular membrane, expanding and receiving the intestines. It begins loosely upon . the loins, extending to all the intestines, except the duodenum; but that part of it which belongs to the large intestines is called mesocolon, and is a production of the true mesentery. The diameter of this circular membrane is somewhat more than four inches, and the circumference when its plaits are unfolded are about three ells in length: the intestines plaited on this circumference are nearly three times that length. The inner membrane is most strictly its own; and in it the vessels and the glands are found. The two exterior ones are from the peritonaeum, and between these the arteries and veins lie, whose branches arc dispersed on the intestines. It confines the intestines, and sustains the arteries, veins, lymphaeducts, and nerves, in their ge to and from them. Many disorders are described by different authors as arising from the mesentery; but Dr. Hunter thinks it is rarely the seat of disease; and that even its glands, sometimes disordered in children, are not affected so frequently as is suspected. Riverius, in the chapter on obstructions in the mesenteric glands, observes that the causes and cure are the same as in similar disorders of the liver. See Praxis Medica, lib. Xiii.