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The lesser omentum (small omentum or gastrohepatic omentum) is the double layer of
The lesser omentum is extremely thin, and is continuous with the two layers of
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.
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 mesotheli ...
that extends from the liver
The liver is a major metabolic organ (anatomy), organ exclusively found in vertebrates, which performs many essential biological Function (biology), functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of var ...
to the lesser curvature of the stomach, and to the first part of the duodenum
The duodenum is the first section of the small intestine in most vertebrates, including mammals, reptiles, and birds. In mammals, it may be the principal site for iron absorption.
The duodenum precedes the jejunum and ileum and is the shortest p ...
. The lesser omentum is usually divided into these two connecting parts: the hepatogastric ligament, and the hepatoduodenal ligament.
Structure
The lesser omentum is extremely thin, and is continuous with the two layers 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 mesotheli ...
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 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 omental foramen.
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: (, ) * hepatogastric ligament: the portion connecting to the lesser curvature of the stomach * hepatoduodenal ligament: 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 thethoracic diaphragm
The thoracic diaphragm, or simply the diaphragm (; ), is a sheet of internal Skeletal striated muscle, skeletal muscle in humans and other mammals that extends across the bottom of the thoracic cavity. The diaphragm is the most important Muscles ...
* hepatoesophageal ligament: the portion connecting to the esophagus
The esophagus (American English), oesophagus (British English), or œsophagus (Œ, archaic spelling) (American and British English spelling differences#ae and oe, see spelling difference) all ; : ((o)e)(œ)sophagi or ((o)e)(œ)sophaguses), c ...
- "Abdominal Cavity: The Lesser Omentum"
* hepatocolic ligament: the portion connecting to the colon
Contents
Between the two layers of the lesser omentum, close to the right free margin, are the hepatic artery proper, thecommon bile duct
The common bile duct (also bile duct) is a part of the biliary tract. It is formed by the union of the common hepatic duct and cystic duct. It ends by uniting with the pancreatic duct to form the ampulla of Vater (hepatopancreatic ampulla). ...
, 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, 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.
Additional images
See also
* Omental bursa (Lesser sac
The lesser sac, also known as the omental bursa, is a part of the peritoneal cavity that is formed by the lesser omentum, lesser and greater omentum. Usually found in mammals, it is connected with the greater sac via the omental foramen or ''For ...
)
* Greater sac
* Omental foramen (Epiploic foramen
In human anatomy, the omental foramen (epiploic foramen, foramen of Winslow after the anatomist Jacob B. Winslow, or uncommonly aditus; ) is the passage of communication, or foramen, between the greater sac, and the lesser sac of the peritone ...
, Foramen of Winslow)
*
*
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