Review Question - QID 217218

This patient whose resected bowel segment has 3 longitudinally organized bands most likely suffered an injury to the colon with disruption of the associated teniae coli.

Each segment of the gastrointestinal tract has a unique histological profile and different macroscopic organizational features. The colon has mucosa with a smooth surface that is devoid of villi and composed of epithelial cells. A prominent feature of this segment is the existence of crypts of Lieberkuhn, also known as intestinal glands, which generate new epithelial cells and secrete luminal material. Macroscopically, the colon is surrounded by circular smooth muscle that is involved in contraction and colonic motility. There are also 3 longitudinally oriented bands of smooth muscle known as teniae coli that organize the activity of the underlying circular smooth muscle to promote smooth contractions. Specifically, they allow each ring of intestinal contractions to finish before the next one begins, promoting forward movement of material through the digestive tract. A diverticulum can develop at the margins of these teniae coli.

Huang et al. studied whether the relative position of a colonic polyp relative to the teniae coli could be used to localize all relevant features on radiography. They found that the teniae coli are extractable landmarks that could be used effectively in determining location within the colon. They recommend using these methods to better identify landmarks in the colon.

Incorrect Answers:
Answer 2: The duodenum is composed of a layer of epithelial cells that are organized in villi. The characteristic feature of this segment is the presence of Brunner glands that secrete alkaline fluid to neutralize acidic chyme.

Answer 3: The ileum is composed of a layer of epithelial cells that are organized in villi. The characteristic feature of this segment is the presence of Peyer patches that are aggregations of encapsulated lymphatic tissue. This segment also has circularly arranged transverse folds known as plicae circulares, or circular folds.

Answer 4: The jejunum is composed of a layer of epithelial cells that are organized in villi. The characteristic feature of this segment is crypts of Lieberkuhn similar to those found in the colon; however, this segment has circularly arranged transverse folds known as plicae circulares, or circular folds, rather than longitudinal teniae coli.

Answer 5: The stomach is composed of gastric mucosa covered by a thick layer of mucus. The characteristic feature of this segment is the presence of gastric glands, which are simple branched tubes that extend from the muscularis externa to the bottom of gastric pits.

Bullet Summary:
The colon has 3 longitudinal bands of smooth muscle known as teniae coli that organize the contractile function of the surrounding circular smooth muscle.