Pancreas

Q: What is the innervation of the pancreas?

The pancreas receives mixed autonomic innervation. Sympathetic innervation — derived from the celiac plexus (plexus coeliacus) and superior mesenteric plexus (plexus mesentericus superior); forms the pancreatic plexus (plexus pancreaticus) around the arteries.Parasympathetic innervation — provided by branches of the vagus nerve (n. vagus).

Q: With which duct does the main pancreatic duct unite?

The main pancreatic duct unites with the common bile duct (ductus choledochus), forming the hepatopancreatic ampulla.

For medical students3 min readUpdated 2026-10-10

The pancreas is a large, unpaired gland belonging to the digestive and endocrine systems, located in the retroperitoneal space on the posterior abdominal wall. The bulk of its tissue produces digestive enzymes, while specialized cell clusters secrete hormones directly into the bloodstream.

SkeletotopyAt the level of the 11th–12th thoracic and 1st–2nd lumbar vertebrae

Weight and dimensionsLength 16–22 cm, weight approximately 70–80 g

StructureLobulated, grayish-pink parenchyma

Venous drainageDrains into the portal vein system (*v. portae*)

General Topography and Microanatomy

The pancreas is situated deep in the abdominal cavity, posterior to the stomach. It lies almost transversely across the vertebral column: approximately one-third of the organ is to the right of the midline, and two-thirds are to the left. It projects onto the anterior abdominal wall in the epigastric and left hypochondriac regions, 5–10 cm above the umbilicus.

Functionally and morphologically, the organ is divided into two parts:

Exocrine part (pars exocrina pancreatis) — constitutes the bulk of the gland. It has a complex tubuloacinar structure. The parenchyma is divided by connective tissue septa (septa interlobares) into lobules (lobi pancreatis). The smallest structural units are pancreatic acini (acini pancreatis), formed by glandular epithelium.
Endocrine part — represented by pancreatic islets (insulae pancreaticae), which are located between the lobules and secrete hormones into the bloodstream.

Macroscopic Structure: Parts of the Gland

Anatomically, the pancreas is divided from right to left into three successive parts: the head, body, and tail.

Head (caput pancreatis)

This is the widest part of the organ, located at the level of the L1–L2 vertebrae. It is tightly embraced by the C-shaped loop of the duodenum. The lower right margin of the head forms the uncinate process (processus uncinatus), directed to the left. At the transition to the body, the gland narrows to form the neck (collum pancreatis). Beneath the neck lies the pancreatic notch (incisura pancreatis), through which the superior mesenteric vessels pass. Syntopy of the head:

Posteriorly: right renal vein, renal artery, inferior vena cava. The neck contacts the abdominal aorta and the right crus of the diaphragm.
Anteriorly: covered by parietal peritoneum, crossed by the root of the transverse mesocolon. The upper part projects into the lesser sac (bursa omentalis) and abuts the posterior wall of the stomach.

Body (corpus pancreatis)

Located at the level of the L1 vertebra, the body is triangular in cross-section. It presents three surfaces (anterosuperior, anteroinferior, and posterior) and three borders (superior, anterior, inferior). The root of the transverse mesocolon attaches to the anterior border. The posterior surface rests against the aorta, celiac plexus, left kidney, left suprarenal gland, and renal vein.

Tail (cauda pancreatis)

The narrow terminal part that extends upward and to the left. It reaches the visceral surface of the spleen, lying between the layers of the gastrosplenic ligament (lig. gastrosplenicum). Inferiorly, the tail contacts the left colic flexure.

Duct System

The exocrine secretion collects into the main pancreatic duct (ductus pancreaticus). It begins in the tail, courses through the body to the head (closer to the posterior surface of the organ), receiving interlobular and intralobular tributaries along its path.

In the region of the right border of the head, the pancreatic duct unites with the common bile duct (ductus choledochus). Together, they form the hepatopancreatic ampulla (ampulla hepatopancreatica), which opens into the lumen of the duodenum at the apex of the major duodenal papilla (papilla duodeni major). Just before the junction, the muscular layer of the pancreatic duct thickens to form its own sphincter (m. sphincter ductus pancreatici).

Note: Some individuals possess an accessory pancreatic gland (pancreas accessorium) — isolated nodules of glandular tissue in the wall of the stomach or small intestine, unconnected to the main organ.

Blood Supply, Innervation, and Lymphatic Drainage

The pancreas is richly vascularized from multiple sources:

Superior pancreaticoduodenal artery (a. pancreaticoduodenalis superior) — a branch of the gastroduodenal artery.
Inferior pancreaticoduodenal artery (a. pancreaticoduodenalis inferior) — arises from the superior mesenteric artery.
Pancreatic branches (rr. pancreatici) — arise from the splenic artery (a. splenica) and primarily supply the body and tail.

Venous blood drains via corresponding veins into the superior and inferior mesenteric, splenic, and left gastric veins. Ultimately, all venous blood collects into the portal vein system (v. portae).

Lymph drains into an extensive network of regional nodes: pancreatic, pancreaticoduodenal, splenic, pyloric, and lumbar lymph nodes. The gland is innervated by branches of the vagus nerve (n. vagus) and sympathetic fibers from the celiac plexus (plexus coeliacus).

Mnemonic

To easily remember the three surfaces of the pancreatic body, use their orientation: the anterosuperior surface 'faces' the stomach, the anteroinferior surface points downward into the abdominal cavity, and the posterior surface lies flat against the posterior abdominal wall and major vessels.

Frequently asked questions

Which anatomical structures are in contact with the posterior surface of the pancreatic head?

The posterior surface of the pancreatic head rests against major blood vessels and the diaphragm, contacting the following structures:

Right renal vein — abuts the posterior surface of the head.
Renal artery — lies adjacent to the posterior surface.
Inferior vena cava — contacts the posterior surface.
Right crus of the diaphragm — touches the region of the neck and the left margin of the uncinate process.
Abdominal aorta — also contacts the left margin of the uncinate process near the neck.

What hormones are produced by the pancreatic islets?

The pancreatic islets secrete hormones into the blood that regulate carbohydrate metabolism and digestion. Different types of islet cells synthesize specific hormones:

Insulin — produced by beta (B) cells.
Glucagon — synthesized by alpha (A) cells.
Somatostatin — produced by delta (D) cells.
Vasoactive intestinal peptide (VIP) — produced by D1 cells.
Pancreatic polypeptide — synthesized by PP cells, stimulates pancreatic and gastric juice secretion.

Where does the accessory pancreatic duct open?

The accessory pancreatic duct opens into the lumen of the duodenum.

Minor duodenal papilla (papilla duodeni minor) — the site where the accessory duct (ductus pancreaticus accessorius) most commonly empties independently.

This papilla is located 3–4 cm proximal (superior) to the major duodenal papilla.

What is the innervation of the pancreas?

The pancreas receives mixed autonomic innervation.

Sympathetic innervation — derived from the celiac plexus (plexus coeliacus) and superior mesenteric plexus (plexus mesentericus superior); forms the pancreatic plexus (plexus pancreaticus) around the arteries.
Parasympathetic innervation — provided by branches of the vagus nerve (n. vagus).

Which organs contact the anterosuperior surface of the pancreatic body?

The anterosuperior surface of the pancreatic body is in contact with the stomach. The body of the organ is prismatic in shape and lies at the level of the first lumbar vertebra.

Posterior wall of the stomach — the anterosuperior surface (facies anterosuperior) of the pancreatic body directly faces this structure.

From which embryonic primordia does the pancreas develop?

The pancreas develops from two endodermal outgrowths of the primitive duodenum:

Dorsal bud (dorsal anlage) — appears first as a diverticulum of the dorsal wall of the gut; it forms the neck, body, tail, and part of the head.
Ventral bud (ventral anlage) — develops more caudally as a diverticulum of the developing bile duct at its entry point into the duodenum.

Where is the tail of the pancreas located?

It points upward and to the left, reaching the visceral surface and hilum of the spleen, situated within the gastrosplenic ligament.

With which duct does the main pancreatic duct unite?

The main pancreatic duct unites with the common bile duct (ductus choledochus), forming the hepatopancreatic ampulla.

What structure is formed by the right lower margin of the pancreatic head?

The right lower margin of the head curves downward and forms the uncinate process (processus uncinatus), directed to the left.

Go deeper

Topography of the omental bursa and its walls
Anatomy and sphincter apparatus of the major duodenal papilla
Histological structure of the pancreatic acinus
Formation of the portal vein and venous drainage of unpaired abdominal organs