“The Omentum (Latin for "apron") is a medical term referring to layers of peritoneum that surround abdominal organs … The greater omentum … is a large apron-like fold of visceral peritoneum that hangs down from the stomach … The greater omentum is larger than the lesser omentum, which hangs down from the liver to the lesser curvature.” (Wikipedia)
“The common anatomical term "epiploic" derives from "epiploon", from the Greek epipleein, meaning to float or sail on, since the greater omentum appears to float on the surface of the intestines.” (Wikipedia)
There’s an interesting, graphic, comparison of a healthy omentum and a not-so-healthy one here:
The omentum has, amongst other things, immune functions using white filters called milky spots for the surrounding fluids. These milky spots are very small white-coloured areas of lymphoid tissue.
A June 2017 review by the University of Alabama reported that, “the fluid around the abdominal organs doesn't just sit there, it circulates through the milky spots …Milky spots collect cells, antigens, and bacteria before deciding what's going to happen immunologically."
Galen states, “It is in this way, therefore, that the stomach, when it is in need of nourishment and the animal has nothing to eat, seizes it from the veins in the liver. Also in the case of the spleen we have shown in a former passage[384] how it draws all material from the liver that tends to be thick, and by working it up converts it into more useful matter. There is nothing surprising, therefore, if, in the present instance also, some of this should be drawn from the spleen into such organs as communicate with it by veins, _e.g._ the omentum, mesentery, small intestine, colon, and the stomach itself. Nor is it surprising that the spleen should disgorge its surplus matters into the stomach at one time, while at another time it should draw some of its appropriate nutriment from the stomach.” (our italics)
Ayurvedic medicine has it as secondary tissue, upadhaatu, as part of fat tissue, medodhatu, that which supports and nourishes the fatty tissue, as part of lubrication and energy storage. Part of the element of water.
Dr Louis Gordon ventured that the omentum may the gut of the brain. In Traditional Chinese Medicine the brain is the “sea of marrow”. It may be possible to see the omentum as the stomach’s “sea of marrow” and also connected to the Triple Warmer meridian.
Image
Dr. Johannes Sobotta [Public domain]