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The greater omentum is a large apron-like fold of visceral peritoneum that hangs down from the stomach.
The greater omentum extends from the greater curvature of the stomach, passing in front of the small intestines and doubles back to ascend to the transverse colon before reaching to the posterior abdominal wall.
It passes in front of the small intestines, sometimes as low as the pelvis, before turning on itself, and ascending as far as the transverse colon, where it separates and encloses that part of the intestine.
It is larger than the lesser omentum which hangs down from the liver to the lesser curvature.
It appears to float on the surface of the intestines, and is the first structure observed when the abdominal cavity is opened anteriorly.
The greater omentum is the larger of the two peritoneal folds, and consists of a double sheet of peritoneum, folded on itself so that it has four layers.
The two layers of the greater omentum descend from the greater curvature of the stomach and the beginning of the duodenum.
The individual layers are easily seen in the young, but are more or less inseparably blended in adults.
The left border of the greater omentum is continuous with the gastrosplenic ligament.
The right border of the greater omentum extends as far as the beginning of the duodenum.
The greater omentum is usually thin, but contains some adipose tissue, which can accumulate to considerably size in obese people.
The greater omentum encompasses a variety of structures:
Gastrophrenic ligament―extends to the underside of the left dome of the diaphragm
Gastrocolic ligament―extends to the transverse colon
Gastrosplenic ligament-extends to the spleen, overlying the kidney
The splenorenal ligament, from the left kidney to the spleen, is also occasionally considered part of the greater omentum.
Blood supply is from the right and left gastroepiploic arteries
The right and left gastroepiploic arteries provide the sole blood supply to the greater omentum.
The right and left gastroepiploic arteries are branches of the celiac trunk.
The functions of the greater omentum are:
Fat deposition.
Immune contribution, having macrophage collections
Infection and wound isolation; limiting the spread of intraperitoneal infections.
Omentectomy refers to the surgical removal of the omentum
Omentectomy is performed in cases where there is concern that there may be spread of cancerous tissue into the omentum.