Title: Small intestine: Anatomy, location and function | Kenhub
Headings: Small intestine
Small intestine: want to learn more about it?
Small intestine
Contents
Anatomy
Duodenum
Jejunum
Ileum
Histology
Function
Blood vessels
Innervation
Clinical relations
Duodenal ulcer
Small intestine: want to learn more about it?

Content: These muscular fibers form a muscular ring within the fold called the ileocecal sphincter which controls the emptying of ileal content into the large intestine. Histology
Histologically, the small intestine has four layers. From internal to external, they are m ucosa, s ubmucosa, m uscularis externa, and s erosa. These layers are easy to remember using the mnemonic M. S. M. S. There are several unique features in the small intestine, which act to significantly increase its absorptive surface: Circular folds (valves of Kerckring, plicae circulares) are the transverse folds of mucosa found predominantly in the distal duodenum and proximal jejunum
Intestinal villi are fingerlike extensions of intestinal mucosa which project into the lumen of the small intestine. Between the villi are intestinal glands (crypts of Lieberkuhn) which secrete intestinal juice rich in digestive enzymes. Microvilli are projections found on the apical surface of each intestinal cell (enterocyte)
There are also features of the small intestine which are segment-specific: Peyer's patches are part of gastrointestinal associated lymphoid tissue (GALT). They are found in ileum. Brunner glands are found in the submucosa of the duodenum.