PERITONEUM

large membrane in the abdominal cavity that connects and supports internal organs. It is composed of many folds that pass between or around the various organs. Two folds are of primary concern: the omentum, which hangs in front of the stomach and intestines; and the mesentery, which attaches the small intestine and much of the large intestine to the posterior abdominal cavity. The omentum and mesentery contain blood vessels, nerves, lymph nodes, varying amounts of fat, elastic fibres for stretching, and collagen fibres for strength. The omentum is thinner than the mesentery and is lacy in appearance. It contains large quantities of fat that serve to keep the organs warm. The mesentery is fan-shaped and well supplied with blood vessels that radiate to the intestines. The functions of these membranes are to prevent friction between closely packed organs by secreting serum that acts as a lubricant, to help hold the abdominal organs in their proper positions, to separate and unite organs, and to guard as a barrier against infection.