Which artery supplies the lower two-thirds of the spinal cord?

• A. Anterior spinal artery
• B. Posterior spinal artery
• C. Intercostal artery
• D. Arteria radicularis magna

Answer: (D)

The blood supply to the spinal cord is organized so the front two-thirds are fed mainly by the anterior spinal artery, while the back one-third is supplied by the posterior spinal arteries. For the lower portion of the cord, a large segmental medullary artery — the artery of Adamkiewicz, also called the great radicular artery — provides the major reinforcement to the anterior spinal artery. It usually arises from a left intercostal or lumbar artery around T9–L2 and travels to join the anterior spinal artery, delivering substantial blood flow to the lower thoracic and lumbar segments. Because this artery is the principal source boosting the anterior supply to the lower cord, it’s the best answer for which vessel supplies the lower two-thirds of the spinal cord. The other options either feed the posterior third or are general segmental feeders rather than the key contributor to the lower cord’s perfusion.