Plicae circulares
Plicae circulares
Also known as: circular folds, valves of Kerckring, valvulae conniventes
Plicae circulares are permanent, crescent-shaped folds of mucosa and submucosa in the small intestine. They roughly triple the absorptive surface and slow the passage of chyme.
Overview
Unlike gastric rugae, plicae circulares do not flatten when the bowel is distended, because they have a core of submucosa. Most run one-half to two-thirds of the way around the lumen, and some form complete rings or spirals. They are up to about 1 cm high. They begin in the second part of the duodenum, are largest and most numerous in the distal duodenum and proximal jejunum, and become progressively lower and sparser in the ileum until they disappear in the terminal ileum.
As well as enlarging the surface, they make chyme follow a spiralling path. This slows transit and improves mixing and contact with the mucosa.
- Location
Small intestine, from the 2nd part of the duodenum to the mid- or distal ileum.
Anatomy
- Histology
Each fold has a submucosal core covered by mucosa bearing villi and crypts.
Function
- Increase the mucosal surface about threefold.
- Slow and swirl the chyme to improve mixing and absorption.
Clinical significance
Radiological sign
On abdominal radiographs of dilated small bowel, the valvulae conniventes cross the entire width of the lumen ("stack of coins"). Colonic haustral folds cross only part of the lumen, which helps distinguish small from large bowel obstruction.
Compiled from standard anatomy and physiology references — see the Digestive System sources. For education only; not medical advice.