posterior spinal arteries, one of two arteries that originate in the cranial cavity, usually arising directly from a terminal branch of each vertebral artery, and descend along the spinal cord, each as two branches that bracket the posterolateral sulcus and the connection of posterior roots with the spinal cord. They are reinforced along their length by 8 to 10 segmental medullary arteries, the largest of which is the artery of Adamkiewicz.
