The left gastric artery supplies blood to the lower curvature of the stomach along with its counterpart, the right gastric artery. The lower curvature of the stomach, also called the greater curvature, is the large, curving surface of the left side of the stomach.

The two arteries have different points of origin, with the left gastric branching off from the celiac trunk while the right gastric originates from the proper hepatic artery. Branches of the left gastric also supply blood to the lower portion of the esophagus.

The artery runs along the bottom of the lower curvature of the stomach, while the right gastric artery runs along the top portion of the curvature. The two arteries interlock to allow undisturbed blood flow to the tissues of the stomach.

Severe peptic ulcer disease — open sores in the stomach lining — can damage the left gastric artery if ulcers become bad enough to degrade the stomach lining and allow stomach acid to come in contact with the artery itself. This can result in large amounts of blood leaking into the stomach, causing blood to be present in bowel movements and may result in the throwing up of blood as well. Untreated, this can lead to massive blood loss.