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Peritoneum.

A thin membrane which lines the whole internal surface of the abdomen, and envelops more or less completely the several parts of the viscera, retaining them in their proper places, and at the same time allowing them to move freely when required.

A serous membrane, which lines the abdominal cavity, Peritonaeum parietale, extends over the greater part of the organs contained there, Peritonaeum intestinale seu viscerale, envelops them wholly or in part, and maintains their respective relations by means of different prolongations and ligamentous folds: - the mesentery, epiploon, mesocolon, &c. Like all the serous membranes, the peritoneum, except in the female, is a sort of sac without aperture, which covers the abdominal organs, without containing them within it, and the internal surface of which is smooth, and lubricated by a serous fluid. In the male foetus, the peritonaeum furnishes a prolongation, which accompanies the testicle at the time of its descent, and, in the female foetus, forms the Canal of Nuck. Below the neck of the gall-bladder, the peritonaeum has a triangular opening, called the Foramen or Hiatus of Winslow, through which it proceeds behind the stomach, to form a sort of secondary cavity, called the posterior cavity of the peritonceum, (F.) Arriere cavite peritoneale ou Cavite des Epiploons.