Serosa of stomach

The serosa of stomach is the outermost layer of the gastric wall and is formed by the visceral peritoneum. It consists of a surface layer of mesothelium (squamous epithelium with basement membrane) supported by a thin layer of connective tissue known as the subserosa. The serosa gives the stomach a smooth, glistening appearance and provides a low-friction surface that allows the organ to expand, contract, and move freely against adjacent abdominal structures during digestion.

Extent of serosal covering

As an intraperitoneal organ, the stomach is almost completely covered by serosa. However, the serosal covering is interrupted at a few sites. Along the greater and lesser curvatures, where the layers of peritoneum are reflected to form the greater omentum and lesser omentum, small triangular areas are left uncovered. These areas provide passage for the gastric blood vessels, lymphatics, and nerves as they enter and leave the stomach. In addition, a small area on the posterior surface near the cardiac orifice is not covered by peritoneum and lies in direct contact with the inferior surface of the diaphragm.

Peritoneal attachments

The serosa is continuous with the peritoneal ligaments attached to the stomach:

• Along the lesser curvature, it is reflected to form the lesser omentum, while

• along the greater curvature it continues into the greater omentum, gastrosplenic ligament, and gastrophrenic ligament.

These peritoneal reflections suspend the stomach within the abdominal cavity and provide pathways for vessels, lymphatics, and nerves.

Subserosa

Beneath the serosa lies the subserosa, a thin layer of loose connective tissue containing small blood vessels, lymphatics, nerves, and variable amounts of adipose tissue. The subserosa firmly anchors the serosa to the underlying muscular coat of the stomach.