Final answer:
A bleeding duodenal ulcer commonly involves the gastroduodenal artery, which is a branch of the celiac trunk that supplies blood to the duodenum.
Step-by-step explanation:
The question refers to the source of bleeding in a patient with a duodenal ulcer. When a duodenal ulcer bleeds, it is typically because the ulcer has eroded a blood vessel. The primary blood supply to the duodenum, including where ulcers commonly form, is from the gastroduodenal artery, a branch of the celiac trunk. The celiac trunk is one of the major arteries that branches off from the abdominal aorta and supplies blood to the liver, stomach, and duodenum. In severe cases of uncontrolled bleeding where endoscopic or medical therapy is not successful, surgical intervention might be required to mend the damaged vessel and control the hemorrhage.