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Lesser omentum
The primitive mesentery of a six weeks’ human embryo, half schematic. (Lesser omentum labeled at left.)
Schematic and enlarged cross-section through the body of a human embryo in the region of the mesogastrium, at end of third month.
Latin	omentum minus
Gray's	subject #246 1156
MeSH	Omentum
Dorlands/Elsevier	o_03/12589823

The lesser omentum (small omentum; gastrohepatic 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.

Contents 1 Structure 2 Divisions 3 Contents 4 Additional images 5 See also 6 References 7 External links

The lesser omentum is extremely thin, and is continuous with the two layers of peritoneum 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 lesser curvature of the stomach and the upper border of the duodenum, they join together and ascend as a double fold to the porta hepatis.

To the left of the porta the fold is attached to the bottom of the fossa for the ductus venosus, 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 epiploic foramen.

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:^[1]

• hepatogastric ligament: the portion connecting to the lesser curvature of the stomach
• hepatoduodenal ligament: the portion connecting to the duodenum

Some sources include additional divisions:

• hepatophrenic ligament: the portion connecting to the thoracic diaphragm^[2]
• hepatoesophageal ligament: the portion connecting to the esophagus^[3]

Between the two layers of the lesser omentum, close to the right free margin, are the hepatic artery, the common bile duct, the portal vein, lymphatics, and the hepatic plexus of nerves—all these structures being enclosed in a fibrous capsule (Glisson's capsule).

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.

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

Horizontal disposition of the peritoneum in the upper part of the abdomen.

• Peritoneum
• Greater omentum

1. ^ Norman/Georgetown abdominalcavity (peritoneumonsagcut, xsectthrulesseromentum)
2. ^ SUNY Labs 38:st-0304 - "Stomach, Spleen and Liver: Ligaments"
3. ^ SUNY Labs 37:05-0103 - "Abdominal Cavity: The Lesser Omentum"

• SUNY Figs 37:04-01 - "The stomach and lesser omentum."
• SUNY Labs 37:05-0100 - "Abdominal Cavity: The Lesser Omentum"
• SUNY Labs 38:03-0102 - "Stomach, Spleen and Liver: Contents of the Hepatoduodenal Ligament"
• SUNY Anatomy Image 7823
• SUNY Anatomy Image 8147
• Anatomy at UMich peritoneal_dev_module/peritoneal_06

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.