This organ is far from fragmented and complex. It is simply one continuous structure,” the study published in The Lancet Gastroenterology & Hepatology says. Its function is still poorly understood, and studying it could be the key to better understanding and treatment of abdominal and digestive disease. The world’s best-known series of medical textbooks, Gray’s Anatomy, has even been updated to include the new definition. Mesentery is a double fold of peritoneum – the lining of the abdominal cavity – that attaches our intestine to the wall of our abdomen, and keeps everything locked in place. “This is relevant universally as it affects all of us,” the study said.