General topography and microanatomy
The pancreas is located deep in the abdominal cavity, behind the stomach. It lies almost transversely, crossing the vertebral column: approximately one-third of the organ is to the right of the midline, and two-thirds to the left. On the anterior abdominal wall, the gland projects into the epigastric and left hypochondriac regions, 5–10 cm above the umbilical ring.
Functionally and morphologically, the organ is divided into two parts:
- Exocrine part (pars exocrina pancreatis) — makes up the bulk of the gland. It has a complex alveolar-tubular 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 has three consecutively positioned parts from right to left: the head, body, and tail.
Head (caput pancreatis)
This is the widest part of the organ, located at the level of the I–II lumbar vertebrae. It is tightly encircled by the horseshoe-shaped loop of the duodenum. The right lower edge of the head forms the uncinate process (processus uncinatus), directed to the left. At the point of transition into the body, the gland narrows, forming the neck (collum pancreatis). Below the neck is 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 the parietal peritoneum, crossed by the root of the transverse mesocolon. The upper part protrudes into the omental bursa (bursa omentalis) and abuts the posterior wall of the stomach.
Body (corpus pancreatis)
Located at the level of the first lumbar vertebra and has the shape of a triangular prism. It features 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 is adjacent to the aorta, celiac plexus, left kidney, adrenal gland, and renal vein.
Tail (cauda pancreatis)
A narrow part directed upwards and to the left. It reaches the visceral surface of the spleen, lying between the leaves of the gastrosplenic ligament (lig. gastrosplenicum). Inferiorly, the tail contacts the left colic flexure.
Duct system
The secretion of the exocrine part collects into the main pancreatic duct (ductus pancreaticus). It begins in the tail, passes through the body to the head (closer to the posterior surface of the organ), receiving intralobular and interlobular ducts along the way.
In the region of the right margin of the head, the pancreatic duct merges 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 its major duodenal papilla (papilla duodeni major). Just before the junction, the muscular layer of the pancreatic duct thickens, forming its own sphincter (m. sphincter ductus pancreatici).
Note: Some individuals have an accessory pancreas (pancreas accessorium) — isolated nodules of glandular tissue in the wall of the stomach or small intestine, not connected to the main organ.
Blood supply, innervation, and lymphatic drainage
The pancreas is richly supplied with blood from several sources:
- Superior pancreaticoduodenal artery (a. pancreaticoduodenalis superior) — a branch of the gastroduodenal artery.
- Inferior pancreaticoduodenal artery (a. pancreaticoduodenalis inferior) — branches off from the superior mesenteric artery.
- Pancreatic branches (rr. pancreatici) — branch off from the splenic artery (a. splenica) and supply mainly the body and tail.
Venous outflow occurs via veins of the same name into the superior and inferior mesenteric, splenic, and left gastric veins. All blood ultimately collects into the portal vein (v. portae) system.
Lymph drains into an extensive network of regional nodes: pancreatic, pancreatoduodenal, 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).
Briefly: answers to topical questions
Which anatomical structures are in contact with the posterior surface of the pancreatic head?
The posterior surface of the pancreatic head is adjacent to major blood vessels and the diaphragm. It is in contact with the following anatomical structures:
- Right renal vein — lies adjacent to 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 — contacts in the region of the neck with the left margin of the uncinate process.
- Abdominal aorta — also contacts the left margin of the uncinate process in the neck region.
Which hormones are produced by the pancreatic islets?
The pancreatic islets produce hormones that enter the blood and regulate carbohydrate metabolism and digestion. Different types of insular 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) — is the site where the accessory duct (ductus pancreaticus accessorius) most often independently empties.
This papilla is located 3–4 cm above the major duodenal papilla.
How is the pancreas innervated?
The pancreas receives mixed autonomic innervation.
- Sympathetic innervation — comes from the celiac plexus (plexus coeliacus) and superior mesenteric plexus (plexus mesentericus superior); the pancreatic plexus (plexus pancreaticus) forms around the arteries.
- Parasympathetic innervation — provided by branches of the vagus nerve (n. vagus).
Which organs are in contact with 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 has a prismatic shape and is located at the level of the first lumbar vertebra.
- Posterior wall of the stomach — it is precisely this wall that the anterosuperior surface (facies anterosuperior) of the pancreatic body faces.
From which embryonic primordia does the pancreas develop?
The pancreas develops from two primordia originating from the entoderm of the primitive duodenum.
- Dorsal anlage (dorsal anlage) — appears first as a diverticulum of the dorsal wall of the intestine; the neck, body, tail, and part of the head form from it.
- Ventral anlage (ventral anlage) — develops more caudally as a diverticulum of the developing bile duct at the site of its entry into the duodenum.
To easily memorize the three surfaces of the pancreas body, use their names as a guide: the anterosuperior surface "faces" the stomach, the anteroinferior surface faces downward into the abdominal cavity, and the posterior surface lies closely against the posterior abdominal wall and major vessels.
Class and exam questions
Where is the tail of the pancreas located?
It is directed to the left and upward, reaching the visceral surface and hilum of the spleen, located within the gastrosplenic ligament.
Which duct does the pancreatic duct join?
The main pancreatic duct joins the common bile duct (ductus choledochus) to form the hepatopancreatic ampulla.
What does the right margin of the pancreatic head form?
The right inferior margin of the head turns downward and forms the uncinate process (processus uncinatus), directed to the left.
What else to study on this topic
- 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 blood drainage from unpaired abdominal organs
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