Major Duodenal Papilla

Overview

The major duodenal papilla is a small, raised structure in the wall of the duodenum through which bile and pancreatic enzymes are released into the small intestine. It serves as the outlet for the common bile duct and the main pancreatic duct and plays a critical role in digestion by delivering digestive juices into the gastrointestinal tract. Its patency and regulation are essential for proper digestion and prevention of biliary or pancreatic disease.

Location

The major duodenal papilla is located in the second part of the duodenum

• Is found on the posteromedial wall of the duodenum

• Approximately 7–10 cm distal to the pylorus

• Lies near the level of the L2 vertebra and is visible during endoscopy as a small mound or bulge

It marks the junction between the foregut and midgut embryologically.

Structure

The major duodenal papilla consists of:

• Mucosal elevation: A small, visible bulge covered by intestinal epithelium

• Opening (orifice): Central slit or hole where the hepatopancreatic ampulla (ampulla of Vater) opens into the duodenum

• Sphincter of Oddi: A complex of smooth muscle that surrounds the terminal portion of the bile and pancreatic ducts; it regulates flow and prevents reflux

Sometimes, a second opening called the minor duodenal papilla exists proximally, draining the accessory pancreatic duct.

Function

The primary function of the major duodenal papilla is to:

• Serve as the drainage site for the common bile duct and the main pancreatic duct

• Deliver bile and pancreatic enzymes into the duodenum to assist in digestion

• Act as a barrier: The sphincter of Oddi prevents backflow of duodenal contents into the ducts

Physiological Role(s)

The major duodenal papilla is involved in several key physiological processes:

• Initiation of digestion: Receives bile (for fat emulsification) and pancreatic enzymes (for breakdown of proteins, carbohydrates, and fats)

• pH neutralization: Bicarbonate-rich pancreatic secretions help neutralize acidic chyme entering from the stomach

• Hormonal regulation: Its activity is controlled by digestive hormones like cholecystokinin (CCK) and secretin

• Sphincter relaxation: The sphincter of Oddi relaxes during digestion to allow flow, and contracts during fasting to prevent reflux

Clinical Significance

The major duodenal papilla is a critical site in multiple clinical conditions and procedures:

• Gallstones: Stones from the gallbladder may lodge at or near the papilla, causing obstructive jaundice or pancreatitis

• Pancreatitis: Obstruction at the papilla can cause backflow of pancreatic enzymes, leading to inflammation and auto-digestion of the pancreas

• Ampullary carcinoma: A rare cancer that originates in the ampulla of Vater, often causing painless jaundice, and detectable via endoscopy

• Sphincter of Oddi dysfunction: A motility disorder causing biliary-type pain and abnormal drainage of bile/pancreatic fluid

• Endoscopic retrograde cholangiopancreatography (ERCP): A diagnostic and therapeutic procedure where a scope is passed to the papilla to access the biliary and pancreatic ducts

• Papillotomy (sphincterotomy): Endoscopic incision of the papilla is often performed to relieve obstruction or remove stones

Any pathology involving the major duodenal papilla can significantly impact digestion and hepatopancreatic function. It is a key anatomical target in both gastroenterology and surgical procedures.