largest of the medullary arteries which supply the spinal cord by anastomosing with the anterior (longitudinal) spinal artery; it arises from a lower intercostal or upper lumbar artery (on the left side about 65% of the time) supplying most of the blood to the lower two-thirds of the anterior spinal artery. See: medullary arteries of brain, under artery. Syn: artery of Adamkiewicz, great anastomotic artery(3), great radicular artery.