Also called: duodenum jejunum ileum
The small intestine is the longest part of the digestive tract, about six metres in living adults, and consists of the duodenum, jejunum and ileum. It completes digestion and absorbs most nutrients through villi on its inner surface. The superior mesenteric artery supplies most of it, and bile and pancreatic enzymes enter at the duodenum.
| Location | Central abdomen, framed by the large intestine. |
|---|---|
| Structure | Duodenum (C-shaped, retroperitoneal), jejunum and ileum (suspended by the mesentery); plicae circulares, villi and microvilli. |
| Function | Final digestion and absorption of nutrients, vitamins and water. |
| Blood supply | Duodenum: gastroduodenal and superior mesenteric arteries. Jejunum and ileum: superior mesenteric artery. |
| Innervation | Vagus nerve (parasympathetic) and superior mesenteric plexus (sympathetic). |
3D model: BodyParts3D (CC BY 4.0), adult male reference anatomy. Highlighted structure shown with nearby bones for context.
The atlas models the small intestine as many separate pieces grouped under this concept. Its huge surface area comes from folds, villi and microvilli.
The duodenum, jejunum and ileum.
In the jejunum and ileum of the small intestine.
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