Lesser omentum
Encyclopedia
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
.
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.
Most sources divide it into two parts:
, 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.
Peritoneum
The peritoneum is the serous membrane that forms the lining of the abdominal cavity or the coelom — it covers most of the intra-abdominal organs — in amniotes and some invertebrates...
that extends from the liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
to the lesser curvature of the stomach
Lesser curvature of the stomach
The lesser curvature of the stomach, extending between the cardiac and pyloric orifices, forms the right or posterior border of the stomach.It descends as a continuation of the right margin of the esophagus in front of the fibers of the right crus of the diaphragm, and then, turning to the right,...
and the start 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...
.
Structure
The lesser omentum is extremely thin, and is continuous with the two layers of peritoneumPeritoneum
The peritoneum is the serous membrane that forms the lining of the abdominal cavity or the coelom — it covers most of the intra-abdominal organs — in amniotes and some invertebrates...
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
Lesser curvature of the stomach
The lesser curvature of the stomach, extending between the cardiac and pyloric orifices, forms the right or posterior border of the stomach.It descends as a continuation of the right margin of the esophagus in front of the fibers of the right crus of the diaphragm, and then, turning to the right,...
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
Ductus venosus
In the fetus, the ductus venosus shunts approximately half of the blood flow of the umbilical vein directly to the inferior vena cava. Thus, it allows oxygenated blood from the placenta to bypass the liver. In conjunction with the other fetal shunts, the foramen ovale and ductus arteriosus, it...
, 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.
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 ligamentHepatogastric ligamentThe cranial part of the lesser omentum is formed by the hepatogastric ligament , extending between the liver and stomach. The ligament itself consists of a dense cranial portion and the caudal portion...
: the portion connecting to the lesser curvature of the stomach - hepatoduodenal ligamentHepatoduodenal ligamentThe 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:* hepatic artery proper* hepatic portal vein* common bile duct...
: the portion connecting to the duodenum
- hepatophrenic ligamentHepatophrenic ligamentThe Hepatophrenic ligament is a ligament connecting the liver to the diaphragm.It is sometimes considered part of the lesser omentum. It is also sometimes considered part of the coronary ligament. However, it is not a term used by most anatomy resources....
: the portion connecting to the thoracic diaphragmThoracic diaphragmIn the anatomy of mammals, the thoracic diaphragm, or simply the diaphragm , is a sheet of internal skeletal muscle that extends across the bottom of the rib cage. The diaphragm separates the thoracic cavity from the abdominal cavity and performs an important function in respiration... - hepatoesophageal ligament: the portion connecting to the esophagusEsophagusThe esophagus is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach...
Contents
Between the two layers of the lesser omentum, close to the right free margin, are the hepatic arteryHepatic artery
Hepatic artery can refer to:* Common hepatic artery * Hepatic artery proper...
, the common bile duct
Common bile duct
The common bile duct is a tube-like anatomic structure in the human gastrointestinal tract. It is formed by the union of the common hepatic duct and the cystic duct . It is later joined by the pancreatic duct to form the ampulla of Vater...
, the portal vein, lymphatics, and the hepatic plexus
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 of the liver....
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
Gastric arteries
Gastric arteries can refer to:* Right gastric artery* Left gastric artery...
, as well as the gastric veins.