The lesser omentum (small omentum or gastrohepatic omentum) is the double layer of

peritoneum The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as annelids. It covers most of the intra-abdominal (or coelomic) organs, and is composed of a layer of mesoth ...

that extends from the

liver The liver is a major Organ (anatomy), organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of proteins and biochemicals necessary for ...

to the

lesser curvature of the stomach The curvatures of the stomach refer to the greater and lesser curvatures. The greater curvature of the stomach is four or five times as long as the lesser curvature. Greater curvature The greater curvature of the stomach forms the lower left ...

, and to the first part of the

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 m ...

. The lesser omentum is usually divided into these two connecting parts: the

hepatogastric ligament The hepatogastric ligament or gastrohepatic ligament connects the liver to the lesser curvature of the stomach. It contains the right and the left gastric arteries. In the abdominal cavity it separates the greater and lesser sac The lesser ...

, and the

hepatoduodenal ligament The hepatoduodenal ligament is the portion of the lesser omentum extending between the porta hepatis of the liver and the superior part of the duodenum. Running inside it are the following structures collectively known as the portal triad: * hep ...

Structure

The lesser omentum is extremely thin, and is continuous with the two layers of

which cover respectively the antero-superior and postero-inferior surfaces of the stomach and first part of the duodenum. When these two layers reach the

and the upper border of the duodenum, they join and ascend as a double fold to the

porta hepatis The porta hepatis or transverse fissure of the liver is a short but deep fissure, about 5 cm long, extending transversely beneath the left portion of the right lobe of the liver, nearer its posterior surface than its anterior border. It join ...

. To the left of the porta, the fold is attached to the bottom of the fossa for the

ductus venosus In the fetus, the ''ductus venosus'' (Arantius' duct after Julius Caesar Aranzi) shunts a portion of umbilical vein blood flow directly to the inferior vena cava. Thus, it allows oxygenated blood from the placenta to bypass the liver. Compared to ...

, along which it is carried to the diaphragm, where the two layers separate to embrace the end of the esophagus. At the right border of the lesser omentum, the two layers are continuous, and form a free margin which constitutes the anterior boundary of the

omental foramen In human anatomy, the omental foramen (epiploic foramen, foramen of Winslow after the anatomist Jacob B. Winslow, or uncommonly aditus; la, Foramen epiploicum), is the passage of communication, or foramen, between the greater sac (general cavity ...

Divisions

Anatomically, the lesser omentum is divided into ligaments, each starting with the prefix "hepato" to indicate that it connects to the liver at one end. Most sources divide it into two parts: (, ) *

: the portion connecting to the lesser curvature of the stomach *

: the portion connecting to the duodenum In some cases, the following ligaments are considered part of the lesser omentum: * hepatophrenic ligament: the portion connecting to the

thoracic diaphragm The thoracic diaphragm, or simply the diaphragm ( grc, διάφραγμα, diáphragma, partition), is a sheet of internal Skeletal striated muscle, skeletal muscle in humans and other mammals that extends across the bottom of the thoracic cavit ...

* hepatoesophageal ligament: the portion connecting to the

esophagus The esophagus (American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to the ...

- "Abdominal Cavity: The Lesser Omentum" *

hepatocolic ligament The Hepatocolic ligament is an occasional fold of peritoneum that extends from the right side of the lesser omentum and passes from the lower surface of the liver The liver is a major organ only found in vertebrates which performs many essent ...

: the portion connecting to the colon

Between the two layers of the lesser omentum, close to the right free margin, are the

hepatic artery proper The hepatic artery proper (also proper hepatic artery) is the artery that supplies the liver and gallbladder. It raises from the common hepatic artery, a branch of the celiac artery. Structure The hepatic artery proper arises from the common ...

, the

common bile duct The common bile duct, sometimes abbreviated as CBD, is a duct in the gastrointestinal tract of organisms that have a gallbladder. It is formed by the confluence of the common hepatic duct and cystic duct and terminates by uniting with pancreati ...

, the

portal vein The portal vein or hepatic portal vein (HPV) is a blood vessel that carries blood from the gastrointestinal tract, gallbladder, pancreas and spleen to the liver. This blood contains nutrients and toxins extracted from digested contents. Approxima ...

lymphatics The lymphatic vessels (or lymph vessels or lymphatics) are thin-walled vessels (tubes), structured like blood vessels, that carry lymph. As part of the lymphatic system, lymph vessels are complementary to the cardiovascular system. Lymph vessel ...

, and the

hepatic plexus The hepatic plexus, the largest offset from the celiac plexus, receives filaments from the left vagus and right phrenic nerves. It accompanies the hepatic artery, ramifying upon its branches, and upon those of the portal vein in the substance o ...

of nerves—all these structures being enclosed in a fibrous capsule (

Glisson's capsule The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it is ...

). Between the layers of the lesser omentum, where they are attached to the stomach, run the right and left gastric arteries, as well as the gastric veins.

Additional images

File:Gray990.png, Diagrams to illustrate the development of the greater omentum and transverse mesocolon. File:Gray1039.png, Horizontal disposition of the peritoneum in the upper part of the abdomen.

References

External links

* * * * - "The stomach and lesser omentum." * - "Abdominal Cavity: The Lesser Omentum" * - "Stomach, Spleen and Liver: Contents of the Hepatoduodenal Ligament" * * * {{Authority control Abdomen

Structure

Divisions

Contents

Additional images

See also

References

External links