Final answer:
The celiac trunk is the unpaired branch of the abdominal aorta that supplies the liver, stomach, and spleen, giving rise to several important arteries including the hepatic artery proper.
Step-by-step explanation:
The large unpaired branch of the abdominal aorta that supplies the liver, stomach, and spleen is the celiac trunk, also known as the celiac artery. This major branch of the abdominal aorta gives rise to the left gastric artery, supplying blood to the stomach and esophagus, the splenic artery, supplying blood to the spleen, and the common hepatic artery. From the common hepatic artery, the hepatic artery proper originates to supply blood to the liver along with the right gastric artery to the stomach and the cystic artery to the gall bladder.