The duodenum is located between the stomach and the middle part of the small intestine.
After food mixes with stomach acid, it moves into the duodenum where it mixes with bile from the gallbladder and digestive juices from the pancreas.

Common duodenum disorders:

Duodenal ulcer
An ulcer is an open sore on the inner lining of the stomach or upper small intestine. It causes burning and pain anywhere from the breastbone to the navel.

The primary symptoms of a duodenal ulcer are heartburn, severe stomach pain, unplanned weight gain, and a burning sensation felt at the back of the throat.