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The greater omentum (also the great omentum, omentum majus , gastrocolic omentum, epiploön, or, especially in animals, caul) is a large fold of peritoneum
Peritoneum

In higher vertebrates, the peritoneum is the serous membrane that forms the lining of the abdomen — it covers most of the intra-abdominal organs....
 that hangs down from the stomach, and extends from the stomach
Stomach

In most mammals, the stomach is a hollow muscular organ of the gastrointestinal tract involved in the second phase of digestion, following mastication....
 to the posterior abdominal wall after associating with the transverse colon
Transverse colon

The transverse colon the longest and most movable part of the Colon , passes with a downward convexity from the right hypochondrium region across the abdomen, opposite the confines of the epigastric and umbilical zones, into the left hypochondrium region, where it curves sharply on itself beneath the lower end of the spleen, forming the splen...
.

greater omentum is the largest peritoneal fold. It consists of a double sheet of peritoneum
Peritoneum

In higher vertebrates, the peritoneum is the serous membrane that forms the lining of the abdomen — it covers most of the intra-abdominal organs....
, 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
Duodenum

The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms anterior intestine or proximal intestine may be used instead of duodenum....
 pass in front of the small intestine
Small intestine

In vertebrates, including mammals, reptiles, birds, and bony fish, the small intestine is the part of the gastrointestinal tract following the stomach, and is where the vast majority of digestion takes place....
s, sometimes as low down as the pelvis
Pelvis

The pelvis or pelvic girdle is the irregular bone structure located at the base of the spine . In the adult human, it is formed by the sacrum and the coccyx, the caudal part of the axial skeleton, and a pair of hip bones, part of the appendicular skeleton or human leg....
; they then turn upon themselves, and ascend again as far as the transverse colon
Transverse colon

The transverse colon the longest and most movable part of the Colon , passes with a downward convexity from the right hypochondrium region across the abdomen, opposite the confines of the epigastric and umbilical zones, into the left hypochondrium region, where it curves sharply on itself beneath the lower end of the spleen, forming the splen...
, 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
Duodenum

The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms anterior intestine or proximal intestine may be used instead of duodenum....
.

The greater omentum is usually thin, presents a cribriform
Cribriform

Cribriform can refer to:* Cribriform plate* Fascia cribrosa...
 appearance, and always contains some adipose tissue
Adipose tissue

In histology, adipose tissue or fat is loose connective tissue composed of adipocytes. Adipose tissue is derived from lipoblasts. Its main role is to store energy in the form of fat, although it also cushions and Thermal insulation the body....
, 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
Anastomosis

An anastomosis is a network of streams that both branch out and reconnect, such as blood vessels or leaf veins. The term is used in medicine, biology, mycology and geology....
 between the right and left gastroepiploic vessels
Gastroepiploic artery

Gastroepiploic artery is the name of two different arteries serving the stomach and greater omentum:* Left gastro-omental artery, a branch of the splenic artery...
.

The greater omentum can often be found wrapped around areas of infection and trauma.

greater omentum is often defined to encompass a variety of structures.






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The greater omentum (also the great omentum, omentum majus , gastrocolic omentum, epiploön, or, especially in animals, caul) is a large fold of peritoneum
Peritoneum

In higher vertebrates, the peritoneum is the serous membrane that forms the lining of the abdomen — it covers most of the intra-abdominal organs....
 that hangs down from the stomach, and extends from the stomach
Stomach

In most mammals, the stomach is a hollow muscular organ of the gastrointestinal tract involved in the second phase of digestion, following mastication....
 to the posterior abdominal wall after associating with the transverse colon
Transverse colon

The transverse colon the longest and most movable part of the Colon , passes with a downward convexity from the right hypochondrium region across the abdomen, opposite the confines of the epigastric and umbilical zones, into the left hypochondrium region, where it curves sharply on itself beneath the lower end of the spleen, forming the splen...
.

Structure

The greater omentum is the largest peritoneal fold. It consists of a double sheet of peritoneum
Peritoneum

In higher vertebrates, the peritoneum is the serous membrane that forms the lining of the abdomen — it covers most of the intra-abdominal organs....
, 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
Duodenum

The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms anterior intestine or proximal intestine may be used instead of duodenum....
 pass in front of the small intestine
Small intestine

In vertebrates, including mammals, reptiles, birds, and bony fish, the small intestine is the part of the gastrointestinal tract following the stomach, and is where the vast majority of digestion takes place....
s, sometimes as low down as the pelvis
Pelvis

The pelvis or pelvic girdle is the irregular bone structure located at the base of the spine . In the adult human, it is formed by the sacrum and the coccyx, the caudal part of the axial skeleton, and a pair of hip bones, part of the appendicular skeleton or human leg....
; they then turn upon themselves, and ascend again as far as the transverse colon
Transverse colon

The transverse colon the longest and most movable part of the Colon , passes with a downward convexity from the right hypochondrium region across the abdomen, opposite the confines of the epigastric and umbilical zones, into the left hypochondrium region, where it curves sharply on itself beneath the lower end of the spleen, forming the splen...
, 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
Duodenum

The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms anterior intestine or proximal intestine may be used instead of duodenum....
.

The greater omentum is usually thin, presents a cribriform
Cribriform

Cribriform can refer to:* Cribriform plate* Fascia cribrosa...
 appearance, and always contains some adipose tissue
Adipose tissue

In histology, adipose tissue or fat is loose connective tissue composed of adipocytes. Adipose tissue is derived from lipoblasts. Its main role is to store energy in the form of fat, although it also cushions and Thermal insulation the body....
, 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
Anastomosis

An anastomosis is a network of streams that both branch out and reconnect, such as blood vessels or leaf veins. The term is used in medicine, biology, mycology and geology....
 between the right and left gastroepiploic vessels
Gastroepiploic artery

Gastroepiploic artery is the name of two different arteries serving the stomach and greater omentum:* Left gastro-omental artery, a branch of the splenic artery...
.

The greater omentum can often be found wrapped around areas of infection and trauma.

Subdivisions

The greater omentum is often defined to encompass a variety of structures. Most sources include the following three:
  • Gastrocolic ligament
    Gastrocolic ligament

    The gastrocolic ligament is a portion of the greater omentum connecting to the transverse colon.External links...
     - to transverse colon
    Transverse colon

    The transverse colon the longest and most movable part of the Colon , passes with a downward convexity from the right hypochondrium region across the abdomen, opposite the confines of the epigastric and umbilical zones, into the left hypochondrium region, where it curves sharply on itself beneath the lower end of the spleen, forming the splen...
     (occasionally on its own considered synonymous with "greater omentum")
  • Gastrosplenic ligament
    Gastrosplenic ligament

    The gastrosplenic ligament is part of the greater omentum.Embryonically the gastrosplenic ligament is derived from the dorsal mesogastrium....
     - to spleen
    Spleen

    The spleen is an organ found in all vertebrate animals. In humans, the spleen is located in the abdomen of the body, where it functions in the destruction of redundant red blood cells, and holds a reservoir of blood....
  • Gastrophrenic ligament
    Gastrophrenic ligament

    The postero-inferior surface of the stomach is covered by peritoneum, except over a small area close to the cardiac orifice; this area is limited by the lines of attachment of the gastrophrenic ligament, and lies in apposition with the Thoracic diaphragm, and frequently with the upper portion of the left suprarenal gland....
     - to thoracic diaphragm
    Thoracic diaphragm

    In the anatomy of mammals, the thoracic diaphragm is a sheet of muscle extending across the bottom of the ribcage. The diaphragm separates the thoracic cavity from the abdominal cavity and performs an important function in Respiration ....


The splenorenal ligament
Splenorenal ligament

The splenorenal ligament , is derived from the peritoneum, where the wall of the general peritoneal cavity comes into contact with the omental bursa between the left kidney and the spleen; the lienal vessels pass between its two layers....
 (from the left kidney
Kidney

The kidneys are Organ that have numerous biological roles. Their primary role is to maintain the homeostasis balance of bodily fluids by filtering and secreting Metabolomics#Metabolitess and minerals from the blood and excreting them, along with water , as urine....
 to the spleen
Spleen

The spleen is an organ found in all vertebrate animals. In humans, the spleen is located in the abdomen of the body, where it functions in the destruction of redundant red blood cells, and holds a reservoir of blood....
) is occasionally considered part of the greater omentum.

Development

The greater omentum develops from the dorsal mesentery
Dorsal mesentery

The portion of mesentery attached to the greater curvature of the stomach is named the dorsal mesentery , and the part which suspends the Colon is termed the mesocolon....
 that connects the stomach
Stomach

In most mammals, the stomach is a hollow muscular organ of the gastrointestinal tract involved in the second phase of digestion, following mastication....
 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
Lesser sac

The lesser sac, also known as the omental bursa, is the cavity in the abdomen that is formed by the lesser omentum and greater omentum. Usually found in mammals, it is connected with the greater sac via the epiploic foramen ....
) 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.

Omentectomy

Omentectomy refers to the surgical removal of the omentum, a relatively simple procedure with no major side effects, that is performed in cases where there may be spread of cancerous tissue into the omentum. Examples for this conditions are ovarian cancer
Ovarian cancer

Ovarian cancer is a malignant tumor arising from an ovary. Although ovarian cancer is known to occur in many species, the majority of the medical literature and the focus of this article is on ovarian cancer in humans....
 and advanced or aggressive endometrial cancer
Endometrial cancer

Endometrial cancer refers to several types of cancer which arise from the endometrium, or lining of the uterus. Endometrial cancers are the most common gynecologic cancers in the United States, with over 35,000 women diagnosed each year in the U.S....
 as well as intestinal cancer. The procedure is generally done as an add-on when the primary lesion is removed.

Additional images


See also

  • Peritoneum
    Peritoneum

    In higher vertebrates, the peritoneum is the serous membrane that forms the lining of the abdomen — it covers most of the intra-abdominal organs....
  • Lesser omentum
    Lesser omentum

    The lesser omentum is the double layer of peritoneum that extends from the liver to the lesser curvature of the stomach and the start of the duodenum....
  • Right gastroepiploic vein
    Right gastroepiploic vein

    The right gastroepiploic vein receives branches from the greater omentum and from the lower parts of the antero-superior and posteroinferior surfaces of the stomach; it runs from left to right along the greater curvature of the stomach between the two layers of the greater omentum....
  • Omental cake
    Omental cake

    In radiology, omental cake is a term used to describe an abnormally thickened appearance of the greater omentum. Typically, it is caused by infiltration of metastases tumours arising from the gastric cancer, ovarian cancer and colon cancer....
  • Caul fat
    Caul fat

    Caul fat is the fatty membrane which surrounds organ s of some animals, such as cows, sheep, and pigs, also known as the greater omentum. It is often used as a natural sausage casing and to encase faggot s or p?t?....


External links