Answer:
The circular folds or kerckring valve, are formations of the mucosa of the small intestine in the form of folds that start in the submucosa and go to the periphery reaching a length of 5 to 8 mm, are located in the final part of the duodenum and more abruptly in the jejunum and taking part of the ileum. Its main function is to increase the capacity of intestinal absorption as to delay the digestion of the chyme.