[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Abdomen](https://durgical.com/en/anatomy/region/abdomen/) › Duodenum [Digestive system](https://durgical.com/en/anatomy/system/digestive-system/) · [Abdomen](https://durgical.com/en/anatomy/region/abdomen/) # Duodenum The duodenum is the C-shaped first part of the small intestine, right after the [stomach](https://durgical.com/en/anatomy/stomach/); bile and pancreatic juice enter it to digest food. [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=abdomen&select=duodenum&side=r) Opens in the Durgical app, no sign-up needed. ## What it is The C-shaped first part of the small intestine, around the head of the pancreas. ## What it does Receives food from the stomach and digestive juices from the liver (bile) and pancreas. ## Key points - The gastroduodenal artery runs behind the first part (D1): a posterior duodenal ulcer can erode it and bleed heavily; anterior D1 ulcers tend to perforate instead - The major duodenal papilla ([ampulla of Vater](https://durgical.com/en/anatomy/hepatopancreatic-ampulla/)), where the bile duct and main pancreatic duct open, is on the posteromedial wall of the second part (D2) - The third part (D3) runs between the superior mesenteric artery and vein in front and the aorta and inferior vena cava behind; a narrow angle compresses it (SMA syndrome) - Mostly retroperitoneal: a rupture of D2–D4 after a blow to the upper [abdomen](https://durgical.com/en/anatomy/region/abdomen/) may give few early signs ## Key facts **Where** C-shaped, about 25 cm, around pancreatic head, L1–L3; D1 superior, D2 descending, D3 horizontal, D4 ascending; retroperitoneal except proximal D1 **Blood supply** Superior pancreaticoduodenal (gastroduodenal, celiac) and inferior pancreaticoduodenal (SMA) arteries; supraduodenal artery for D1 **Nerve** Vagus and sympathetic fibres via celiac and superior mesenteric plexuses **Function** Receives chyme plus bile and pancreatic juice at major papilla (D2); neutralizes acid; secretin and CCK; iron absorption ## Relations **Course** D1 runs right and back from the pylorus at L1; D2 descends to the right of L1–L3; D3 crosses to the left at L3; D4 rises to the duodenojejunal flexure at L2, held by the suspensory muscle of the duodenum (ligament of Treitz) **In front** D1: [liver](https://durgical.com/en/anatomy/liver/) and [gallbladder](https://durgical.com/en/anatomy/gallbladder/); D2: [transverse colon](https://durgical.com/en/anatomy/transverse-colon/) and the root of the transverse [mesocolon](https://durgical.com/en/anatomy/mesocolon/); D3: [superior mesenteric artery](https://durgical.com/en/anatomy/superior-mesenteric-artery/) and vein and the root of the mesentery **Behind** D1: [gastroduodenal artery](https://durgical.com/en/anatomy/gastroduodenal-artery/), [bile duct](https://durgical.com/en/anatomy/bile-duct/) and [portal vein](https://durgical.com/en/anatomy/hepatic-portal-vein/); D2: right [kidney](https://durgical.com/en/anatomy/kidney/) and renal vessels; D3: right [ureter](https://durgical.com/en/anatomy/ureter/), right psoas, [inferior vena cava](https://durgical.com/en/anatomy/inferior-vena-cava/) and aorta; D4: left psoas **Medial** Head of the [pancreas](https://durgical.com/en/anatomy/pancreas/), cradled in its C-shaped curve, with the pancreaticoduodenal arcades between them; the bile duct and main [pancreatic duct](https://durgical.com/en/anatomy/pancreatic-duct/) enter D2 here **Above** D1 forms the lower border of the epiploic foramen (of Winslow), with the hepatoduodenal ligament attached to its upper edge **Lateral** D2: right colic (hepatic) flexure and the right lobe of the liver ## How to find it Not palpable. At endoscopy the duodenal bulb (cap) lies just past the pylorus; the major papilla is reached on the posteromedial wall of D2 with a side-viewing scope (ERCP). In surgery the Kocher maneuver, incising the [peritoneum](https://durgical.com/en/anatomy/peritoneum/) lateral to D2 and sweeping it medially with the head of the pancreas, exposes its back. ## On imaging A barium meal outlines the triangular duodenal cap; a widened C-loop suggests a mass in the head of the pancreas. CT shows its relation to the superior mesenteric artery and aorta. On a newborn's X-ray, the double-bubble sign (gas in the stomach and proximal duodenum only) points to duodenal atresia or obstruction. ## Common problems - Duodenal ulcer: burning pain, often eased by food; can bleed or perforate. ## How it is diagnosed Examination, X-ray or CT, endoscopy, blood tests. ## Treatment - Depends on the cause: rest and fluids for many obstructions, medicines for Crohn disease, surgery for some. ## Clinical notes - The Kocher maneuver exposes D2, the head of the pancreas and the distal bile duct, and starts a pancreaticoduodenectomy (Whipple procedure) - Retroperitoneal duodenal injury from handlebar or seat-belt trauma; retroperitoneal air may outline the right kidney on X-ray - Periampullary tumors (pancreatic head, distal bile duct, ampulla, duodenum) block bile flow early and cause painless jaundice ## Anatomical variants - Pancreas divisum: the dorsal and ventral pancreatic ducts do not join, so most of the gland drains through the minor duodenal papilla, above and in front of the major one; the commonest congenital variant of the pancreas, usually silent - Annular pancreas: a ring of pancreatic tissue around the second part (D2); uncommon, it can narrow the duodenum and cause vomiting in the newborn or later in life ## Development It comes from the end of the foregut and the start of the midgut, which meet just below the major papilla; that is why both the [celiac trunk](https://durgical.com/en/anatomy/celiac-trunk/) and the superior mesenteric artery supply it. Failed recanalization causes duodenal atresia, associated with Down syndrome. ## Related conditions - [Peptic ulcer disease](https://durgical.com/en/conditions/peptic-ulcer-disease/) - [Upper gastrointestinal bleeding](https://durgical.com/en/conditions/upper-gastrointestinal-bleeding/) - [Coeliac disease](https://durgical.com/en/conditions/coeliac-disease/) - [Infantile hypertrophic pyloric stenosis](https://durgical.com/en/conditions/infantile-hypertrophic-pyloric-stenosis/) - [Abetalipoproteinemia (Bassen–Kornzweig syndrome)](https://durgical.com/en/conditions/abetalipoproteinemia/) - [Zinc deficiency (acrodermatitis enteropathica)](https://durgical.com/en/conditions/zinc-deficiency/) - [Iron deficiency anaemia](https://durgical.com/en/conditions/iron-deficiency-anaemia/) - [Iron poisoning](https://durgical.com/en/conditions/iron-poisoning/) - [Zollinger-Ellison syndrome (gastrinoma)](https://durgical.com/en/conditions/zollinger-ellison-syndrome/) - [Functional dyspepsia](https://durgical.com/en/conditions/functional-dyspepsia/) - [Pancreatic neuroendocrine tumours (VIPoma, glucagonoma, somatostatinoma, non-functioning)](https://durgical.com/en/conditions/pancreatic-neuroendocrine-tumours/) - [Giardiasis](https://durgical.com/en/conditions/giardiasis/) - [Strongyloidiasis](https://durgical.com/en/conditions/strongyloidiasis/) - [Down syndrome (trisomy 21)](https://durgical.com/en/conditions/down-syndrome/) - [Duodenal and intestinal atresia](https://durgical.com/en/conditions/duodenal-and-intestinal-atresia/) - [Intestinal malrotation with midgut volvulus](https://durgical.com/en/conditions/intestinal-malrotation-with-midgut-volvulus/) ## Test yourself Think of the answer, then tap the question to see it. ## Which artery can a posterior ulcer of the first part of the duodenum erode? The gastroduodenal artery, which runs behind D1, causing heavy bleeding; anterior D1 ulcers tend to perforate instead. ## Where does the major duodenal papilla open? On the posteromedial wall of the second part of the duodenum (D2), where the bile duct and main pancreatic duct open. ## Between which vessels does the third part of the duodenum pass? Between the superior mesenteric artery and vein in front and the aorta and IVC behind; a narrow angle compresses it (SMA syndrome). ## What is the Kocher maneuver? Incising the peritoneum lateral to D2 and sweeping the duodenum and pancreatic head medially, exposing their back and the distal bile duct. ## What does the double-bubble sign on a newborn's X-ray suggest? Duodenal atresia or obstruction: gas only in the stomach and proximal duodenum. [Add to my cards (5)](https://durgical.app/estudiar/?add=/en/anatomy/duodenum/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** duodenum TA2 2944 **Official Spanish (DeCS)** Duodeno DeCS D004386 **English (TA2)** Duodenum **Also called** intestinum duodenum ## Related - [Stomach](https://durgical.com/en/anatomy/stomach/) - [Pancreas](https://durgical.com/en/anatomy/pancreas/) - [Ampulla of Vater](https://durgical.com/en/anatomy/hepatopancreatic-ampulla/) - [Celiac trunk](https://durgical.com/en/anatomy/celiac-trunk/) - [Gastroduodenal artery](https://durgical.com/en/anatomy/gastroduodenal-artery/) - [Superior mesenteric artery](https://durgical.com/en/anatomy/superior-mesenteric-artery/) Sources: Terminologia Anatomica (TA2); [DeCS](https://decs.bvsalud.org/es/ths/resource/?id=4446); [Anatomy, Abdomen and Pelvis: Duodenum](https://www.ncbi.nlm.nih.gov/books/NBK482390/). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/duodenum/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/duodenum/