After the duodenum, the jejunum leads the way in the small intestine.

Outline (brief skeleton)

• Opening hook: why knowing the small bowel lineup matters when reading CTs and answering board-style questions.

• Quick anatomy refresher: duodenum, jejunum, ileum — plus where each sits and what sets them apart.

• Why the jejunum matters on CT: folds, wall pattern, and vascular feel that help you spot it.

• How to recognize the jejunum on scans: practical cues, location cues, and contrast behavior.

• Common pitfalls to avoid: confusing segments, or mixing up with the stomach or colon.

• A tiny memory aid and a quick recap tied to the NMTCB CT board context.

• Final thought: how this tidy map helps you approach abdominal imaging with confidence.

Jejunum on the map: a friendly guide to the small bowel lineup

Let me explain a simple truth that makes a big difference when you’re reading CT images: the small intestine is a three-part relay race. The duodenum starts things off, the jejunum follows, and the ileum brings up the rear. In radiology land, that sequence isn’t just trivia; it’s a mental compass that helps you orient scans quickly, especially when you’re juggling multiple cross-sectional images or chasing subtle abnormalities.

First, a quick refresher. The small bowel is divided into three segments:

• Duodenum: the first, relatively short stretch right after the stomach, receiving chyme and beginning the chemical digestion kick.

• Jejunum: the middle portion, famous for its heavy role in nutrient absorption.

• Ileum: the final stretch, where bile acids and vitamin B12 reabsorption happen and where lymphoid tissue becomes a bit more pronounced.

The pylorus, by the way, sits at the boundary of the stomach and duodenum, not as part of the small bowel itself. And the colon—ah, the colon—belongs to the large intestine. It’s easy to mix things up if you don’t keep the borders straight, so let’s keep that clear in our heads as we move along.

Why the jejunum matters when you’re reading a CT

You’ll hear radiologists talk about the jejunum as a “workhorse” section of the small bowel, given its role in absorbing nutrients. On imaging, some practical cues point toward the jejunum:

• Fold pattern: the jejunum tends to have more prominent circular folds (plicae circulares) than the ileum, which makes its mucosal pattern more evident on contrast-enhanced CT.

• Wall characteristics: the jejunum often shows a relatively thicker wall with robust enhancement after IV contrast, reflecting its rich blood supply.

• Mesenteric layout: the mesentery around the jejunum tends to look somewhat looser in the central abdomen, with long vasa recta that can be visualized if you’re tracing vessels on a high-quality CT.

• Location tendencies: while there’s some mixing, the jejunum usually sits more centrally and upperly in the abdomen, whereas the ileum can drift toward the right lower quadrant.

All of this matters because, on a board-style question, you’re asked to identify structures quickly and reason about their function or pathology. If you can name the section and connect it to its typical imaging features, you already have a leg up on many tricky questions.

How to spot the jejunum on a CT in real life (with a practical, not-too-dramatic approach)

Here’s a straightforward way to keep the jejunum in sight when you’re scrolling through axial slices:

• Start with the landmarks: locate the stomach, then the duodenum as the initial small-bowel segment. From there, the next stretch along the alimentary tract is the jejunum. If you’re unsure, trace the small bowel from the stomach, then follow the loops toward the central abdomen.

• Look for folds and wall texture: the jejunum will often show denser, more conspicuous folds on a single slice, and your contrast-enhanced study should reveal a relatively robust wall intensity.

• Observe the vessels: the mesenteric vessels fan out toward the jejunal loops; if you can spot the longer vasa recta, you’re likely looking at the jejunum rather than the ileum.

• Compare with the ileum: if you’re unsure whether you’ve found the middle or the end of the small bowel, check the folds—folds tend to become less conspicuous in the ileum, and the ileum may have more prominent lymphoid tissue on certain sequences or phases, though this isn’t always obvious on every CT.

• Don’t confuse with the colon or stomach: the colon has haustral markings that are quite distinct, and the pylorus is a stomach structure at the entry to the duodenum. Keeping these borders in mind helps prevent mislabeling.

A tiny memory aid that’s handy on those long reading days

If you like a little mental shortcut, the order of the small-bowel segments is a reliable anchor: Duodenum → Jejunum → Ileum. A simple cue like “D-J-I” can become second nature after a few scans. It’s not fancy, but it works when you’re scanning quickly and don’t want to stall on orientation.

Connecting this to the NMTCB CT board landscape

You might wonder why a paragraph about folds and vasa recta belongs in board-focused content. Here’s the real deal: board-style questions often test not just raw facts, but the ability to connect anatomy with imaging appearance and clinical context. Understanding the orderly sequence of the small bowel improves your speed and accuracy in answering questions about scans of the abdomen. It also aids in recognizing where pathology is likely to show up and which segments are more prone to certain conditions, such as inflammatory processes or post-surgical changes.

To strengthen this, you can lean on trusted resources that align with radiology practice standards. Radiopaedia offers concise image-focused explanations of small-bowel anatomy and common CT appearances. For a broader reference, Gray’s Anatomy provides foundational context, while the American College of Radiology (ACR) guidelines help you think in terms of appropriateness and imaging strategies. These aren’t “cheat sheets”—they’re reference points that ground your interpretations in solid anatomy and imaging logic.

Common traps you’ll want to sidestep

Even seasoned readers slip here. A few recurring slips, and how to sidestep them:

• Mistaking the ileum for the jejunum: if you focus only on size, you might mislabel. Remember the ileum often sits toward the periphery and lower abdomen and tends to have relatively thinner walls with less conspicuous folds on a routine CT.

• Confusing the stomach boundary with small bowel segments: the pylorus is the gateway from stomach to the duodenum, so it’s not a small-bowel segment at all. If you’re unsure, trace from the stomach and watch for the stomach's recognizable thick muscular wall and the abrupt transition to a different pattern.

• Interpreting colon as small bowel: colon folds (haustrations) are a tell. If you see large, pouch-like saculations, you’re probably looking at colon, not jejunum.

A few practical, board-ready takeaways

• Identity matters: knowing the exact sequence—duodenum, jejunum, ileum—gives you a mental map to navigate abdominal CTs quickly.

• Texture and pattern: expect more prominent folds and a robust wall signal in the jejunum compared with the ileum.

• Location cues: central positioning in the upper abdomen and a certain vascular pattern can help you distinguish jejunum from other segments.

• Always cross-check with the stomach and colon boundaries to keep your labeling accurate.

From theory to application: what this means for the CT board mindset

Think of anatomy as your road map. On the NMTCB CT board, you’re often asked to identify where something is, what it’s near, and what it implies about the process in the body. The jejunum’s distinctive features—its folds, its relative wall thickness when contrast is present, and its central abdominal placement—give you vital anchors. When you combine these anchors with a systematic reading approach, you’re not guessing; you’re interpreting.

If you’re ever tempted to rush, slow down long enough to confirm a couple of context clues. For example, if you see a loop that seems to be central and has pronounced folds, check where you are in relation to the stomach and the colon. If you’re in doubt, a quick cross-check with adjacent slices often reveals the transition from jejunum to ileum. Those small checks add up to big confidence on the test day.

A closing thought: your internal map is part of your imaging toolkit

The small-bowel lineup is a quiet hero in abdominal imaging. By having the Jejunum in mind as the segment that follows the duodenum, and by recognizing its telltale imaging cues, you’re equipping yourself with a reliable, repeatable approach. It’s the kind of knowledge that translates to clearer reads, quicker answers, and less guesswork under an exam’s clock. And if you want to sharpen this further, pair anatomy with imaging resources like Radiopaedia or ACR guidelines and use real-world CT examples to anchor the concepts. The result isn’t just theoretical knowledge; it’s practical skill you can carry into any abdominal CT you encounter.

In short: after the duodenum comes the jejunum, the middle segment of the small bowel. Keep that order in your head, watch for the folds and the wall pattern, and you’ll navigate abdominal CTs with a steadier hand and a clearer mind.