Superior part of the duodenumThe duodenum begins at the pyloric sphincter of the stomach. This first part runs back toward the spine before the tube turns down.
Descending part of the duodenumIt is the second part. The common bile duct and the main pancreatic duct empty into it through the major duodenal papilla.
Horizontal part of the duodenumIt is the third part. It passes in front of the inferior vena cava and the abdominal aorta.
Ascending part of the duodenumIt is the fourth part. It rises to join the jejunum, the next region of the small intestine.
Head of the pancreasThe head sits inside the C of the duodenum. The ducts that carry pancreatic juice and bile run through it to the duodenal wall.
Body of the pancreasIt runs to the left across the back of the abdomen. It lies behind the stomach.
Tail of the pancreasThe pancreas tapers to a tail that ends at the spleen's hilum.
SpleenThe spleen lies in the upper left of the abdomen. The splenic artery brings its blood and the splenic vein carries it away toward the liver.
GallbladderA muscular sac that stores and concentrates bile from the liver. It then releases the bile toward the duodenum through the common bile duct.
Ducts 7
Common hepatic ductThe right and left hepatic ducts merge into it. It leaves the liver.
Cystic ductIt links the neck of the gallbladder to the common hepatic duct. Bile passes along it in both directions.
Common bile ductIt carries bile down to the duodenum. It passes behind the first part of the duodenum and through the head of the pancreas.
Main pancreatic ductIt carries pancreatic juice to the duodenum. It joins the common bile duct just before the duodenal wall. Also called the duct of Wirsung.
Accessory pancreatic ductWhen present, it runs from the pancreas straight into the duodenum. It enters above the opening of the main duct. Also called the duct of Santorini.
Hepatopancreatic ampullaThe common bile duct and the main pancreatic duct meet here. A ring of muscle round it controls the flow of bile and pancreatic juice. Also called the ampulla of Vater.
Major duodenal papillaThe ampulla opens into the descending duodenum at this small raised opening.
Vessels 10
Abdominal aortaThe aorta is called the abdominal aorta below the diaphragm. It ends low in the abdomen by splitting into the two common iliac arteries.
Inferior vena cavaIt collects blood from the abdomen, the pelvis and the lower limbs.
Celiac trunkIt divides into three arteries. They are the left gastric, the splenic and the common hepatic.
Left gastric arteryIt supplies the stomach and the lower esophagus.
Common hepatic arteryIt gives rise to the hepatic artery proper, which supplies the liver. It also gives branches for the stomach, gallbladder, duodenum and pancreas.
Splenic arteryIt runs along the upper edge of the pancreas to the spleen.
Superior mesenteric arteryIt supplies the small intestine, pancreas and most of the large intestine. It passes in front of the horizontal part of the duodenum.
Splenic veinIt runs behind the pancreas. It joins the superior mesenteric vein to form the hepatic portal vein.
Superior mesenteric veinIt carries blood from the small intestine. Also from much of the large intestine and the stomach.
Hepatic portal veinIt forms behind the pancreas. The superior mesenteric and splenic veins meet there, and it carries their blood to the liver before it returns to the heart.
How this list was compiled: Every name and detail checked on 2026-09-30 against OpenStax Anatomy and Physiology 2e, sections 23.5 The Small and Large Intestines (the four parts of the duodenum, hepatopancreatic ampulla, major duodenal papilla), https://openstax.org/books/anatomy-and-physiology-2e/pages/23-5-the-small-and-large-intestines, 23.6 Accessory Organs in Digestion (head, body and tail of the pancreas, the pancreatic and accessory ducts, the hepatic, cystic and common bile ducts, the gallbladder), https://openstax.org/books/anatomy-and-physiology-2e/pages/23-6-accessory-organs-in-digestion-the-liver-pancreas-and-gallbladder, and 20.5 Circulatory Pathways (abdominal aorta, celiac trunk and its three branches, superior mesenteric artery, inferior vena cava, hepatic portal system), https://openstax.org/books/anatomy-and-physiology-2e/pages/20-5-circulatory-pathways, and against Wikipedia, Duodenum, Pancreas, Pancreatic duct, Common bile duct, Celiac artery and Portal vein, text only. Licence: own work
The drawing: Drawn for this site on 2026-10-05 by script. Our own drawing, nothing traced. The organs, ducts and vessels were laid out by eye after four public domain plates in Henry Gray, Anatomy of the Human Body (20th US edition, 1918): the duodenum and pancreas after fig. 1098 (https://commons.wikimedia.org/wiki/File:Gray1098.png), the pancreatic ducts after fig. 1100 (https://commons.wikimedia.org/wiki/File:Gray1100.png), the celiac trunk and its branches after fig. 533 (https://commons.wikimedia.org/wiki/File:Gray533.png) and the portal vein after fig. 591 (https://commons.wikimedia.org/wiki/File:Gray591.png). A plan, not to scale: the liver and the stomach are taken away and not drawn, the gallbladder is swung out to the side, the vessels are spread a little so each can be seen, and the splenic artery leaves the celiac trunk nearer the aorta than the other two branches, which in the body leave it together. Licence: own work
How it works
With the stomach and liver lifted away, three drawings show the back of the upper abdomen: the organs, the bile and pancreatic ducts enlarged, and the arteries and veins. It is a drawing, not a photo of any maker's model.
Read the full guide
Organs, then ducts, then vessels
Numbers 1 to 4 follow the duodenum round its C: superior, descending, horizontal, ascending. The pancreas lies in the curve, head (5) to tail (7), and the tail touches the spleen (8). Numbers 10 to 16 follow bile and pancreatic juice down to one opening in the duodenum. Numbers 17 to 26 are the aorta, its branches, and the veins that join to form the hepatic portal vein.
Arteries named for an organ run to it: splenic to the spleen, hepatic to the liver, gastric to the stomach.
The cystic duct and the common hepatic duct join to make the common bile duct.
Questions and answers
What organs are at the back of the upper abdomen?
The duodenum and the pancreas lie against the back wall, behind the stomach, with the spleen at the tip of the pancreas on the left. The abdominal aorta and the inferior vena cava run down behind them.
What are the four parts of the duodenum?
Superior, descending, horizontal and ascending. The tube leaves the stomach, turns down, crosses the body in front of the inferior vena cava and the aorta, then climbs to join the jejunum. Together they make a C round the head of the pancreas.
Where do the bile duct and the pancreatic duct meet?
At the hepatopancreatic ampulla, in the wall of the descending duodenum. The ampulla opens at the major duodenal papilla, so bile and pancreatic juice enter the duodenum through one opening.
What are the three branches of the celiac trunk?
The left gastric artery to the stomach, the splenic artery to the spleen, and the common hepatic artery toward the liver.
Which veins form the hepatic portal vein?
The superior mesenteric vein and the splenic vein meet behind the pancreas to form it. It carries blood from the digestive organs to the liver.