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Stomach Anatomy: Regions, Curvatures, Omenta Attachments, and Wall Features

Capítulo 6

Estimated reading time: 7 minutes

Position and Orientation in the Upper Abdomen

The stomach is a J-shaped, intraperitoneal organ in the upper abdomen, typically occupying the epigastric and left hypochondriac regions. Its long axis runs from the esophageal entry (superior-left) toward the pylorus (inferior-right). Because it is mobile, its exact position varies with body habitus, posture, and degree of filling, but the key relationships remain consistent: it lies inferior to the diaphragm, anterior to the pancreas (separated by the lesser sac), and superior to the transverse colon and its mesentery.

When describing stomach anatomy, keep two reference ideas in mind: (1) the stomach has named regions along the path of food, and (2) it has two curvatures that serve as attachment lines for peritoneal folds (omenta) and as routes for major vessels.

Regions of the Stomach (Cardia, Fundus, Body, Pylorus)

Cardia

The cardia is the region surrounding the opening where the esophagus joins the stomach. It is a short segment just distal to the gastroesophageal junction. In surface terms, it sits near the left side of the midline, deep to the left costal margin. Clinically and anatomically, it is a key transition zone: the esophagus enters at an oblique angle, and the stomach begins to expand laterally and inferiorly.

Fundus

The fundus is the dome-shaped superior portion that lies above the level of the cardial opening. It typically contacts the diaphragm and is often the most superior part of the stomach. On imaging, the fundus is a common site for a gas bubble; in dissection, it is the rounded “cap” on the left side.

Body

The body is the largest central region, extending from the fundus toward the distal stomach. It forms most of the anterior and posterior surfaces and is the main reservoir and mixing chamber. The body is where the stomach’s internal folds (rugae) are most conspicuous when the stomach is empty or partially filled.

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Pylorus

The distal stomach is the pylorus, which leads to the duodenum. It is functionally and anatomically specialized for controlled emptying. The pylorus is commonly subdivided into a wider pyloric antrum and a narrower pyloric canal that ends at the pyloric opening.

Internal Wall Features: Rugae and Their Mechanical Role

The stomach’s mucosa forms prominent longitudinal folds called rugae. These folds are most visible when the stomach is empty and flatten as it distends. Mechanically, rugae support two key actions without requiring you to memorize physiology: (1) distension—the stomach can expand substantially as rugae unfold, and (2) mixing—the folded surface increases internal contouring, helping churn and redistribute contents during gastric movements.

Practical tip: in a specimen, if you open the stomach along the greater curvature, rugae appear as ridges running roughly along the long axis, especially in the body and toward the antrum.

Curvatures as Attachment Lines and Landmark Borders

Lesser curvature

The lesser curvature is the shorter, concave border on the right/superior aspect of the stomach, running from the cardia to the pylorus. It is a crucial landmark because it is where the lesser omentum attaches and where the gastric vessels course close to the stomach wall.

Greater curvature

The greater curvature is the longer, convex border on the left/inferior aspect, sweeping from the fundus down and around to the pylorus. It provides the attachment line for the greater omentum and is closely related to the transverse colon region via that apron-like peritoneal fold.

Omenta Attachments and the Peritoneal Spaces They Define

Lesser omentum: stomach to liver, and the gateway to the lesser sac

The lesser omentum is a peritoneal fold extending from the lesser curvature (and proximal duodenum) to the inferior surface of the liver. In practical anatomy, it forms a thin sheet that you can lift to appreciate the space behind the stomach. This matters because the stomach’s posterior surface faces the lesser sac (omental bursa), a peritoneal space that sits posterior to the stomach and lesser omentum and anterior to the pancreas.

Key spatial idea: the lesser curvature is not just a border—it is a “hinge line” where the stomach connects to the liver via the lesser omentum, and that connection helps outline the anterior boundary of the lesser sac.

Greater omentum: stomach to transverse colon region

The greater omentum attaches along the greater curvature and drapes inferiorly like an apron. It is classically described as descending from the stomach and then turning back to relate to the transverse colon and its mesentery region. When you trace the greater curvature in a dissection, you often find a thick, fatty peritoneal fold that can obscure underlying structures; lifting it helps reveal the transverse colon area and reinforces how the stomach is linked to the lower “floor” of the upper abdomen.

Key spatial idea: the greater curvature is the attachment line that leads you toward the transverse colon region via the greater omentum, while the lesser curvature leads you toward the liver via the lesser omentum.

Pyloric Anatomy and the Gastroduodenal Junction

Pyloric antrum and canal

The pyloric antrum is the expanded distal chamber that funnels contents toward the outlet. Distal to it, the pyloric canal is narrower and more tubular, ending at the pyloric opening. In specimens, the antrum is often identified by its broader diameter compared with the canal.

Pyloric sphincter (anatomical landmark)

At the distal end of the pyloric canal, the circular muscle is thickened to form the pyloric sphincter, which marks the transition to the duodenum. Even without focusing on physiology, treat it as a palpable/visible ring-like landmark that helps you define where the stomach ends.

Gastroduodenal junction

The gastroduodenal junction is the point where the pylorus meets the first part of the duodenum. This junction is a key orientation point in upper abdominal anatomy: it is where the stomach’s thick-walled, rugae-bearing lumen transitions to the duodenum’s different internal patterning. When identifying it, look for the narrowing at the pyloric canal and the immediate continuation into the duodenum.

Practical Identification Sequence (Dissection, Prosection, or Imaging)

Locate the stomach in the upper abdomen. Find the left upper quadrant/epigastrium and identify the J-shaped organ deep to the left costal margin. Confirm the esophagus entering superiorly and the duodenum leaving on the right.
Identify the two curvatures first. Trace the short concave border as the lesser curvature and the long convex border as the greater curvature. This immediately orients you to “liver side” (lesser curvature) versus “apron/colon side” (greater curvature).
Name the regions along the path of flow. Start at the esophageal entry: cardia → move superiorly to the dome: fundus → follow the main chamber: body → follow distally to the widened distal part: pyloric antrum → narrow segment: pyloric canal → ring-like outlet: pylorus.
Open or inspect the lumen to see rugae. If a specimen is available, open along the greater curvature and look for rugae in the body/antrum. If using imaging, recognize that rugae become less prominent as the stomach distends.
Trace the lesser curvature to the liver via the lesser omentum. Lift the thin peritoneal sheet running from the lesser curvature toward the liver. Use this to conceptualize the space behind the stomach (the lesser sac) without re-deriving peritoneal compartment theory.
Trace the greater curvature toward the transverse colon region via the greater omentum. Follow the thick, fatty fold descending from the greater curvature. Reflect it to reveal the transverse colon area and appreciate the stomach’s peritoneal continuity with that region.
Finish at the gastroduodenal junction. Follow the distal stomach to the pyloric canal and identify the transition into the duodenum at the pylorus.

Key Vascular Territories as Named Landmarks (No Deep Physiology)

Use the curvatures as “roads” for naming vessels:

Left gastric artery: runs along the lesser curvature toward the cardia region (a key landmark vessel on the superior/right border).
Right gastric artery: also courses along the lesser curvature, approaching from the distal side toward the pylorus region.
Left gastro-omental (gastroepiploic) artery: runs along the greater curvature on the left side, near the fundus/body region.
Right gastro-omental (gastroepiploic) artery: runs along the greater curvature on the right side, nearer the antrum/pylorus region.
Short gastric arteries: supply the fundus, reaching it near the superior part of the greater curvature.

Practical mapping rule: “Gastric” = lesser curvature; “gastro-omental” = greater curvature; “short gastric” = fundus.

Now answer the exercise about the content:

During a dissection, you want to orient the stomach by using its curvatures to predict peritoneal attachments. Which statement is correct?

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The lesser curvature is the short, concave border that attaches to the liver via the lesser omentum. The greater curvature is the long, convex border that attaches to the transverse colon region via the greater omentum.