Stomach Anatomy (Topography, External Features, Parts, Layers)

Stomach Anatomy

The video reviews the stomach’s location and relationships, its external features and subdivisions, and the layers of its wall.

Location and Connections

• The stomach lies mainly in the epigastric and left hypochondriac regions, broadly corresponding to the left upper quadrant.
• It extends from the abdominal part of the esophagus to the duodenum:
  • The esophagus opens into the stomach at the cardiac orifice, around the T10–T11 vertebral level.
  • The stomach empties into the duodenum through the pyloric orifice, around the L1 vertebral level.

Relationships to Nearby Structures

• Anterior surface: diaphragm, liver, and anterior abdominal wall.
• Posterior surface: left kidney, spleen, pancreas, and transverse colon.

External Features and Parts

The stomach has two curvatures:

• Lesser curvature, which has a depression called the angular notch (incisura angularis).
• Greater curvature, near which is the cardiac notch (incisura cardialis).

Its main parts are:

1. Cardiac part
2. Fundus — the upper, dome-shaped portion
3. Body
4. Pyloric part, divided into:
   • Pyloric antrum, next to the body
   • Pyloric canal, leading to the duodenum

Layers of the Stomach Wall

From the inside outward, the stomach wall consists of the following layers:

Tunica Mucosa

• Forms prominent gastric folds, whose surfaces include smaller regions called areae gastricae.
• Is lined by simple columnar epithelium.
• Contains gastric pits, especially in the fundus and body, associated with cells that produce hydrochloric acid and digestive enzymes.
• Beneath the epithelium is the lamina propria, connective tissue containing blood vessels and small lymphoid nodules.
• Its thin smooth-muscle layer is the muscularis mucosae.

Tela Submucosa

A layer of loose connective tissue containing associated structures, including blood vessels.

Tunica Muscularis

Unlike the usual two-layer arrangement described for much of the digestive tract, the stomach has three smooth-muscle layers:

1. Inner oblique layer
2. Middle circular layer, which forms the pyloric sphincter at the stomach–duodenum junction
3. Outer longitudinal layer, arranged along the curvatures

The presenter distinguishes the pyloric sphincter from the lower esophageal sphincter, which is formed by smooth muscle of the esophagus and helps limit acid from moving upward. Weakness of this sphincter is associated with gastroesophageal reflux and potential damage to the esophageal mucosa.

Tunica Serosa

The outer covering, formed by the peritoneum, provides a smooth, slippery surface.

Speaker and Source

The presenter is Meditay from Taim Talks Med.