Organ
Duodenum
Fixed proximal bowel receiving digestive secretions
High-yield
The major papilla marks the conventional foregut–midgut boundary, but arterial branches overlap in pancreaticoduodenal arcades rather than stopping at the papilla.
Overview
The duodenum links the gastric outlet to the jejunum and curves around the pancreatic head. Its four named portions organize a compact region where the bowel meets major vessels and the biliary and pancreatic ducts. The proximal bulb is relatively mobile; most of the remaining duodenum is attached to the posterior abdominal wall.
Reference facts
- Location
- Between pylorus and duodenojejunal flexure, usually spanning the upper lumbar region around the pancreatic head.
- Parts
- Superior, descending, horizontal and ascending portions; the last turns into jejunum at the duodenojejunal flexure.
- Blood supply
- Gastroduodenal and superior mesenteric branches join through superior and inferior pancreaticoduodenal arcades; proximal duodenal branches add supply near the bulb.
- Innervation
- Vagal parasympathetic input and sympathetic pathways in the celiac/superior mesenteric plexuses; visceral afferents accompany these regional pathways.
- Venous/Lymphatic drainage
- Venous blood reaches portal and superior mesenteric channels; lymph passes through pancreaticoduodenal groups toward celiac and superior mesenteric nodes.
- Relations
- Pancreatic head inside the curve; gastroduodenal artery and bile duct behind the proximal region; superior mesenteric vessels anterior to the horizontal segment.
- Function
- Mixes chyme with bile and pancreatic secretion. Duodenal bicarbonate-rich secretions, including mucus from Brunner glands, help protect the mucosa from acid.
Clinical correlation
Duodenal disease can involve nearby structures as well as the bowel itself: a posterior proximal ulcer may reach the gastroduodenal artery, while narrowing at the third part may relate to the superior mesenteric vessels. These different relationships help localize the anatomical consequences.
Frequently asked questions
Where is the duodenum located?
Between pylorus and duodenojejunal flexure, usually spanning the upper lumbar region around the pancreatic head.
What does the duodenum do?
Mixes chyme with bile and pancreatic secretion. Duodenal bicarbonate-rich secretions, including mucus from Brunner glands, help protect the mucosa from acid.
What are the parts of the duodenum?
Superior, descending, horizontal and ascending portions; the last turns into jejunum at the duodenojejunal flexure.
What is the blood supply of the duodenum?
Gastroduodenal and superior mesenteric branches join through superior and inferior pancreaticoduodenal arcades; proximal duodenal branches add supply near the bulb.