The double layer of peritoneal membrane which supports the small INTESTINE. It is fan shaped, its shorter edge being attached to the back wall of the abdomen for a distance of about 15 cm (6 inches), while the small intestine lies within its longer edge, for a length of over 6 metres (20 feet). The terms mesocolon, mesorectum, etc, are applied to similar folds of PERITONEUM that support parts of the colon, rectum, etc.