A 45-year-old man undergoes a barium meal study for chronic epigastric pain. The radiologist identifies a sharp notch on the lesser curvature of the stomach, marked as **B** in the diagram, which serves as an important anatomic landmark. During subsequent endoscopy, a benign gastric ulcer is found at this exact location. Which of the following statements best describes the clinical significance of the structure marked **B**?

Explanation

## Why "It represents the junction between the gastric body and antrum, and serves as a key endoscopic landmark for localizing gastric ulcers and determining their anatomic level" is right The structure marked **B** is the incisura angularis — a sharp notch on the lesser curvature that anatomically divides the gastric body (proximal) from the antrum (distal). According to Sutton Radiology 7e and Bailey & Love 28e, the incisura angularis is a critical endoscopic landmark used to precisely localize gastric ulcers and other lesions, allowing clinicians to determine whether a lesion is in the body or antrum. This distinction has clinical relevance for prognosis and management. The patient's ulcer location at this anatomic point exemplifies the practical use of this landmark in clinical practice. ## Why each distractor is wrong - **"It marks the junction between the gastric fundus and the gastric body, and is the most common site for fundal varices in portal hypertension"**: The fundus-body junction is marked by the gastroesophageal junction and the gas-filled dome (structure **A**), not the incisura angularis. Fundal varices occur in the fundus itself, not at the incisura. - **"It indicates the transition zone between the antrum and pyloric channel, and is the predilection site for H. pylori-associated gastritis and MALToma"**: The antrum-pyloric channel junction is distal to the incisura angularis. H. pylori has a predilection for the antrum proper, not the incisura. The incisura is the body-antrum boundary, not the antrum-pyloric boundary. - **"It demarcates the pyloric channel from the duodenal cap, and is where the characteristic string sign appears in infantile hypertrophic pyloric stenosis"**: The pyloric channel (structure **C**) and duodenal cap (structure **D**) are distal to the incisura angularis. The string sign appears in the pyloric channel itself in infantile hypertrophic pyloric stenosis, not at the incisura. **High-Yield:** The incisura angularis (lesser curvature notch) = body–antrum junction = endoscopic landmark for ulcer localization and anatomic classification. [cite: Sutton Radiology 7e Ch 25; Bailey & Love 28e Ch 68]