Title: Small Intestine: Anatomy, Function, and Treatment
Headings: The Anatomy of the Small Intestine
The Anatomy of the Small Intestine
The largest digestive organ breaks down food and absorbs nutrients
Anatomy
The Mesentery
The Lymph System and the Small Intestine
Location
Anatomical Variations
Function
Absorption of Nutrients
The Lining of the Small Intestine
The Enteric Nervous System
Associated Conditions
Treatment
Tests

Content: The jejunum lies between the duodenum and the ileum. The anatomy of the three segments of the small intestine includes: The duodenum, the smallest segment of the small intestine, measuring only 10 to 15 inches in length. The duodenum begins where the stomach ends at the pylorus (the valve that opens and closes, allowing food to pass from the stomach into the small intestine). Next, the duodenum curves around the pancreas and ends in the area of the upper left quadrant of the abdomen, where it connects with the jejunum. The ampulla of Vater is an important landmark that serves as the site where the bile duct and the pancreatic duct empty their digestive juices (containing enzymes that help to breakdown ingested food) into the duodenum. The pancreatic and bile ducts form a system called the biliary system (also called the biliary tract) which forms a vital part of the digestive system and attaches to the liver, pancreas and the duodenum. Pancreatic juice and bile (made in the liver and stored in the gallbladder) help with the digestive process by breaking down nutrients (such as fats, proteins, and carbohydrates) so they can be easily absorbed in the small intestine. The jejunum is the upper portion of the small intestine which connects to the duodenum at one end (at the duodenojejunal flexure) and to the ileum at the other end. The jejunum comprises approximately 40% of the small bowel in humans.