Spinal Cord Blood Supply: Anterior, Posterior, and Watershed Syndromes
A clinical anatomy reference for the spinal cord arterial supply — the single anterior spinal artery, paired posterior spinal arteries, segmental supply, and the syndromes from focal ischemia in each territory.
Learning Objectives
- ✓Map the arterial supply of the spinal cord by territory and segmental level.
- ✓Match a spinal cord ischemic syndrome to the involved artery.
- ✓Recognize the surgical and aortic procedures that put the cord at ischemic risk.
1. Direct Answer: One Anterior, Two Posterior, Plus Segmentals
The spinal cord receives arterial blood from three longitudinal vessels reinforced by radicular branches. The ANTERIOR SPINAL ARTERY runs in the anterior median fissure from the medullopontine junction to the conus medullaris, supplying the anterior two-thirds of the cord — including the anterior horns (motor neurons), corticospinal tract, and spinothalamic tract. The PAIRED POSTERIOR SPINAL ARTERIES run along the dorsal surface and supply the posterior one-third — the dorsal columns (fine touch, vibration, proprioception). These three longitudinal vessels alone cannot maintain perfusion over the full cord length; they are supplemented by segmental RADICULAR ARTERIES from the vertebral, intercostal, and lumbar arteries that enter via the intervertebral foramina. The largest of these is the ARTERY OF ADAMKIEWICZ (great anterior radicular artery), which most commonly arises from a left intercostal artery between T9 and L1 (variant range T5 to L5) and supplies the entire lumbosacral cord — a single artery whose ligation can cause paraplegia.
Key Points
- •Anterior spinal artery: anterior two-thirds of cord.
- •Paired posterior spinal arteries: dorsal columns.
- •Artery of Adamkiewicz: dominant lumbosacral supply, typically T9-L1 left intercostal.
2. Anterior Spinal Artery Syndrome
Occlusion or hypoperfusion of the anterior spinal artery produces a classic syndrome of lost motor function (corticospinal tract) and lost pain and temperature sensation (spinothalamic) BELOW the level of the lesion, with PRESERVED proprioception, vibration, and fine touch (dorsal columns supplied by posterior spinal arteries). It is the most common cord vascular syndrome because the anterior spinal artery covers the largest territory and has fewer collaterals than the paired posterior vessels. Causes include aortic dissection or surgery (particularly thoracoabdominal aortic aneurysm repair affecting Adamkiewicz), atherosclerotic embolism, fibrocartilaginous embolism from a herniated disc, and prolonged hypotension during surgery. Imaging may be normal early; MRI may show owl-eye appearance from anterior horn infarction on axial T2 imaging hours to days later.
Key Points
- •Motor and pain/temperature loss below the level; dorsal columns spared.
- •Causes: aortic surgery, dissection, hypotension, fibrocartilaginous embolism.
- •Owl-eye sign on axial T2 MRI from bilateral anterior horn infarction.
3. Posterior Spinal Artery Syndrome
Far less common because of bilateral redundancy. Occlusion produces loss of vibration and proprioception below the level (dorsal columns) with preserved motor function and preserved pain/temperature. Patients walk with a sensory ataxia — wide-based, looking at their feet, worse in darkness. Romberg sign is positive. Causes are similar to anterior cord syndrome but usually require unilateral occlusion to manifest because the paired posterior arteries provide mutual collateral. Some texts include posterior cord syndrome under Brown-Sequard variants, but pure posterior column infarction without lateral or anterior involvement is a discrete entity.
Key Points
- •Loss of vibration and proprioception; motor and pain/temp preserved.
- •Sensory ataxia and positive Romberg.
- •Bilateral redundancy makes this syndrome rare.
4. Central Cord Syndrome
Damage to the central cord (often from hyperextension injury in an older patient with cervical spondylosis) preferentially affects the centrally located corticospinal tract fibers serving the UPPER EXTREMITIES (because the lamination places arm fibers medially in the lateral corticospinal tract) and the central crossing fibers of the spinothalamic tract. The result is more weakness in the arms than legs and a cape-like loss of pain and temperature across the upper trunk and arms with preserved sacral sensation. It is not a vascular syndrome per se but is included here because it can occur from hypoperfusion in a watershed pattern when central cord vasa corona are stressed. Recovery is variable and often incomplete; treatment is largely supportive.
Key Points
- •Arms weaker than legs; cape-like pain/temp loss with sacral sparing.
- •Classic mechanism: hyperextension in older patient with spondylosis.
- •Watershed-pattern central cord ischemia is a contributor in some cases.
5. Watershed Cord Zones and Adamkiewicz
Two watershed zones in the cord are particularly vulnerable to global hypotension. The upper thoracic cord (T1-T4) sits between the cervicothoracic and thoracic-region vascular territories. The lumbosacral cord depends heavily on the single artery of Adamkiewicz, making the conus particularly vulnerable. In thoracoabdominal aortic aneurysm repair, the surgical team monitors for spinal cord ischemia using motor evoked potentials and may employ techniques including reimplantation of intercostal arteries, distal aortic perfusion, lumbar drain placement to reduce CSF pressure, and aggressive blood pressure management — all aimed at protecting the anterior spinal artery and Adamkiewicz supply. Despite these measures, the incidence of cord ischemia after open thoracoabdominal aneurysm repair is approximately 5%–10%.
Key Points
- •Upper thoracic (T1-T4) and lumbosacral zones are most watershed-vulnerable.
- •Aortic surgery puts Adamkiewicz at risk; risk mitigation is multimodal.
- •Even with protection, ~5–10% incidence of cord ischemia in TAAA repair.
6. Internal Cord Anatomy: The Sulcal-Commissural Artery
The anterior spinal artery sends penetrating branches into the cord through the anterior median fissure. The SULCAL-COMMISSURAL ARTERIES branch alternately left and right within the cord, supplying one half of the gray matter at a given level. Because each sulcal artery supplies only ONE side, a focal sulcal artery occlusion can produce an asymmetric Brown-Sequard-like pattern. The CIRCUMFLEX BRANCHES (vasa corona) form a peripheral network around the cord and supply the peripheral white matter. The interior gray matter is supplied by deeper sulcal branches with no significant collaterals, which is why central cord ischemia preferentially damages gray matter in the watershed zone.
Key Points
- •Sulcal arteries alternate left/right and supply one side of gray matter each.
- •Vasa corona supply peripheral white matter via circumferential branches.
- •Central gray matter has the least collateral supply.
7. Using AnatomyIQ for Cord Vascular Localization
Describe the spinal cord exam findings (motor, pain/temp, vibration/proprioception, level) and AnatomyIQ localizes the most likely arterial territory involved, ranks differential causes, and recommends initial imaging. Upload an MRI and the overlay identifies the longitudinal vessels and segmental contributions, including the predicted location of Adamkiewicz based on the involved level. This content is for educational purposes only.
Key Points
- •Exam pattern matched to arterial territory with ranked differential.
- •MRI overlay with longitudinal and segmental vessels.
- •Predicted Adamkiewicz location based on involved cord segment.
High-Yield Facts
- ★Anterior spinal artery: anterior 2/3 of cord (corticospinal, anterior horns, spinothalamic).
- ★Posterior spinal arteries (paired): dorsal columns only.
- ★Artery of Adamkiewicz: typically T9-L1 left intercostal; dominates lumbosacral supply.
- ★Anterior cord syndrome: motor + pain/temp loss; dorsal columns spared.
- ★Central cord syndrome: arms > legs weakness with sacral sparing; classic in spondylotic hyperextension.
Practice Questions
1. A patient develops paraplegia, loss of pain and temperature below T10, and preserved vibration/proprioception after thoracoabdominal aortic surgery. Diagnosis and mechanism?
2. A 70-year-old falls forward in a hyperextension injury. He has weakness greater in his hands than his legs and reports loss of pain and temperature in a cape-like distribution. Diagnosis?
3. A 50-year-old develops sudden sensory ataxia with preserved strength. Sensation to pinprick is normal but vibration and proprioception are absent below the umbilicus. Which artery is involved?
FAQs
Common questions about this topic
Most commonly between T9 and T12 on the left side (about 75% of cases), though the range spans T5 to L5 with right-sided variants. The “arterial of Adamkiewicz” terminology refers specifically to the great anterior radicular artery that joins the anterior spinal artery in the thoracolumbar region — by convention, the largest such radicular contributor. Preoperative imaging (CT angiography, selective angiography) attempts to localize it before aortic surgery.
Three reasons. First, the anterior spinal artery has a larger territory with no redundant longitudinal vessel — there is just one anterior artery vs the paired posterior arteries. Second, the anterior cord territory includes the gray matter (anterior horns), which is more metabolically demanding and ischemia-sensitive than white matter. Third, the largest segmental contributor (Adamkiewicz) feeds primarily into the anterior spinal artery, making it the dominant pathway whose disruption is felt most.
A rare cause of acute spinal cord ischemia in which fragments of nucleus pulposus from an intervertebral disc embolize to spinal arteries — usually after a Valsalva maneuver, trauma, or vigorous activity. It can mimic anterior spinal artery syndrome. It is most often diagnosed at autopsy or by exclusion in young patients with sudden cord ischemia and no other identifiable cause; MRI may show disc abnormalities at the relevant level.
Acutely: blood pressure optimization (often targeting MAP > 85 mm Hg), lumbar drainage to reduce CSF pressure and improve perfusion gradient, and treatment of any underlying cause (anticoagulation if embolic, aortic intervention if dissection). High-dose steroids for traumatic causes are controversial; for purely vascular causes they are not standard. Rehabilitation focuses on preserving residual function, bladder management, and prevention of secondary complications.
Yes. Describe the exam findings — motor, pain/temp, vibration/proprioception, level — and AnatomyIQ ranks the most likely arterial territory involved, suggests an underlying mechanism, and recommends initial imaging. MRI overlay shows the longitudinal vessels and predicted Adamkiewicz location based on the involved cord segment. This content is for educational purposes only.