A 28-year-old man undergoes a barium study for chronic diarrhea. The radiologist notes that the jejunum has prominent circular mucosal folds (plicae circulares) that extend across the entire width of the bowel lumen. Which of the following statements about the jejunum is most accurate?

Explanation

## Distinguishing Features of Jejunum vs. Ileum **Key Point:** The jejunum has **fewer and thicker plicae circulares** (circular mucosal folds) that extend completely across the bowel lumen, whereas the ileum has **more numerous and thinner plicae** that are often interrupted. **Comparative Anatomy:** | Feature | Jejunum | Ileum | |---|---|---| | **Plicae circulares** | Fewer, thicker, complete | More, thinner, interrupted | | **Diameter** | Wider (3–4 cm) | Narrower (2–3 cm) | | **Wall thickness** | Thicker | Thinner | | **Mesentery** | Shorter, less fat | Longer, more fat | | **Peyer's patches** | Absent or sparse | Abundant | | **Vasa recta** | Long, few branches | Short, many branches | **Clinical Pearl:** On barium studies, the jejunum appears as a "**feathery**" or "**ladder-like**" pattern due to prominent, continuous plicae, while the ileum shows a more irregular, "**string of pearls**" appearance due to interrupted folds and Peyer's patches. **High-Yield:** This distinction is crucial for radiological diagnosis and understanding small bowel pathology. Jejunal ulcers (as in Zollinger-Ellison syndrome) are more common than ileal ulcers.