Anterior Spinal Artery — FRCA Primary MCQ
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Correct answer: A — It is unpaired, descends in the anterior median fissure, and supplies the anterior two-thirds of the spinal cord.
The anterior spinal artery is normally an unpaired midline vessel, formed cranially from branches of the vertebral arteries. It descends in the anterior median fissure and supplies approximately the anterior two-thirds of the spinal cord, including the anterior horns and much of the corticospinal and spinothalamic pathways. Its longitudinal supply is reinforced by segmental radiculomedullary arteries, including the variable artery of Adamkiewicz. The posterior columns are supplied predominantly by the paired posterior spinal arteries, so B and C describe the posterior rather than anterior circulation. Anterior spinal artery occlusion therefore causes motor and pain/temperature deficits with relative preservation of dorsal-column modalities; isolated loss of vibration and proprioception in D is the opposite pattern.
Reference: Royal College of Anaesthetists. NAP3: Major Complications of Central Neuraxial Block in the United Kingdom, Chapter 6: Spinal cord ischaemia. 2009. https://www.rcoa.ac.uk/media/32506