Greater omentum

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Greater omentum
Vertical disposition of the peritoneum. Main cavity, red; omental bursa, blue. (Greater omentum labeled at left.)
Diagrams to illustrate two stages in the development of the digestive tube and its mesentery. The arrow indicates the entrance to the bursa omentalis.
Latin	omentum majus
Gray's	subject #246 1157
Precursor	Dorsal mesentery
MeSH	Omentum

The greater omentum (great omentum; gastrocolic omentum; epiploon) is a large fold of peritoneum that hangs down from the stomach, and extends from the stomach to the posterior abdominal wall after associating with the transverse colon.

Structure

The greater omentum is the largest peritoneal fold. It consists of a double sheet of peritoneum, folded on itself so that it is made up of four layers.

The two layers which descend from the stomach and commencement of the duodenum pass in front of the small intestines, sometimes as low down as the pelvis; they then turn upon themselves, and ascend again as far as the transverse colon, where they separate and enclose that part of the intestine.

These individual layers may be easily demonstrated in the young subject, but in the adult they are more or less inseparably blended.

The left border of the greater omentum is continuous with the gastrolienal ligament; its right border extends as far as the commencement of the duodenum.

The greater omentum is usually thin, presents a cribriform appearance, and always contains some adipose tissue, which in obese people accumulates in considerable quantity.

Between its two anterior layers, a short distance from the greater curvature of the stomach, is the anastomosis between the right and left gastroepiploic vessels.

Subdivisions

The greater omentum is often defined to encompass a variety of structures, and can thus be subdivided into the following:

• Gastrophrenic ligament
• Gastrosplenic ligament
• Phrenicosplenic ligament
• Splenorenal ligament
• Pancreaticosplenic ligament
• Pancreaticocolic ligament
• Splenocolic ligament
• Phrenicocolic ligament

Development

The greater omentum develops from the dorsal mesentery that connects the stomach to the posterior abdominal wall. During stomach development, the stomach undergoes its first 90° rotation along the axis of the embryo, so that posterior structures are moved to the left and structures anterior to the stomach are shifted to the right. As a result, the dorsal mesentery folds over on itself, forming a pouch with its blind end on the left side of the embryo. A second approximately 90° rotation of the stomach, this time in the frontal plane, moves structures inferior if they were originally to the left of the stomach, and superior if they were originally to the stomach's right. Consequently, the blind-ended sac (also called the lesser sac) formed by the dorsal mesentery is brought inferiorly, where it assumes its final position as the greater omentum. It grows to the point that it covers the majority of the small and large intestine.

Additional images

The celiac artery and its branches; the liver has been raised, and the lesser omentum and anterior layer of the greater omentum removed.

Schematic figure of the bursa omentalis, etc. Human embryo of eight weeks.

Diagrams to illustrate the development of the greater omentum and transverse mesocolon.

See also

• Peritoneum
• Lesser omentum
• Right gastroepiploic vein
• Omental cake

External links

• SUNY Figs 37:03-07
• SUNY Figs 37:05-12
• SUNY Labs 37:07-0100
• Diagram at Tn.edu
• Photo of model at Waynesburg College digirep/greateromentum

v • d • e Peritoneal ligaments, mesenteries, and folds
From ventral mesentery	Lesser omentum: Hepatoduodenal ligament - Hepatogastric ligament Liver: Coronary ligament (Left triangular ligament, Right triangular ligament, Hepatorenal ligament) - Falciform ligament (Round ligament of liver and Ligamentum venosum in it, but not of it)
From dorsal mesentery	Greater omentum: Gastrophrenic ligament - Gastrocolic ligament - Gastrosplenic ligament Mesentery: Transverse mesocolon - Sigmoid mesocolon - Mesoappendix - Root of the mesentery Splenorenal ligament - Phrenicocolic ligament
Uterus/ovaries	Broad ligament of the uterus (Mesovarium, Mesosalpinx, Mesometrium) - Ovarian ligament - Suspensory ligament of the ovary
Folds	Umbilical folds (Supravesical fossa, Medial inguinal fossa, Lateral inguinal fossa) - Ileocecal fold - Rectouterine folds
Recesses	Rectouterine pouch - Vesicouterine excavation - Rectovesical excavation - Pararectal fossa - Paravesical fossa
Peritoneal cavity	Greater sac - Lesser sac - Foramen of Winslow

de:Omentum majus

it:Grande omento

Acknowledgement and Attribution Regarding Sources of Content

Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .