Final answer:
The anterior spinal artery, which provides blood to the anterior surface of the spinal cord, is supplied by the vertebral arteries, stemming from the subclavian arteries.
Step-by-step explanation:
The anterior spinal artery is a crucial blood vessel that runs along the anterior surface of the spinal cord, providing it with necessary nutrients and oxygen. This artery is supplied by the merged branches of the vertebral arteries, which arise from the subclavian arteries. The vertebral arteries are protected as they traverse the cervical vertebrae and enter the cranium through the foramen magnum. Once inside the skull, these arteries also contribute to the blood supply of the brain by forming the basilar artery and becoming part of the arterial circle, commonly referred to as the circle of Willis.