The spinal cord receives its essential blood supply from a sophisticated network of longitudinal arteries that run along its length, supplemented and reinforced by numerous segmental arteries. This intricate system ensures continuous oxygen and nutrient delivery to this vital part of the central nervous system.
Primary Longitudinal Arteries
The main arterial supply to the spinal cord comes from three principal longitudinal arteries that descend its entire length:
Anterior Spinal Artery (ASA)
The anterior spinal artery is a single vessel that originates from the fusion of branches from the two vertebral arteries at the level of the brainstem. It runs within the anterior median fissure, supplying the anterior two-thirds of the spinal cord, including the anterior and lateral funiculi and the anterior horns.
Posterior Spinal Arteries (PSAs)
The two posterior spinal arteries typically arise directly from the vertebral arteries or from the posterior inferior cerebellar arteries. They descend along the posterolateral sulci, supplying the posterior one-third of the spinal cord, including the posterior funiculi and the posterior horns.
Segmental and Radicular Contributions
While the anterior and posterior spinal arteries form the primary longitudinal channels, their flow is insufficient to supply the entire spinal cord independently. They require reinforcement from numerous segmental radicular arteries (also known as medullary arteries) that enter the spinal canal along the spinal nerves at various levels.
Crucially, the primary longitudinal spinal arteries receive their initial supply from the vertebral arteries predominantly up to the cervical segments of the spinal cord. Inferiorly, these spinal arteries are significantly augmented by blood flow received through a network of lumbar and radicular arteries. These reinforcing arteries arise from different major arteries depending on the spinal cord region:
- Cervical Region: Contributions come from the vertebral arteries themselves, as well as branches of the deep cervical and ascending cervical arteries.
- Thoracic Region: Blood supply is primarily provided by intercostal arteries that branch off the aorta.
- Lumbar and Sacral Regions: The lumbar arteries and lateral sacral arteries, also originating from the aorta, contribute significantly.
Great Anterior Medullary Artery (Artery of Adamkiewicz)
Among the segmental radicular arteries, one is particularly notable for its substantial contribution to the lower spinal cord: the great anterior medullary artery, often called the Artery of Adamkiewicz. This critical vessel typically arises from a lower intercostal or upper lumbar artery (most commonly between T9-L2, usually on the left side) and provides the major blood supply to the thoracolumbar spinal cord, reinforcing the anterior spinal artery in this vulnerable region.
Summary of Spinal Cord Vascular Supply
The following table summarizes the key arterial components supplying the spinal cord:
| Arterial System | Primary Origin/Contribution | Region Supplied Primarily |
|---|---|---|
| Anterior Spinal Artery | Formed by branches of vertebral arteries (cervical segments); reinforced extensively by segmental radicular arteries (e.g., intercostal, lumbar arteries, Artery of Adamkiewicz) which become the dominant supply inferiorly. | Anterior two-thirds of the spinal cord |
| Posterior Spinal Arteries | Typically arise from vertebral arteries or posterior inferior cerebellar arteries (cervical segments); reinforced by segmental radicular arteries (e.g., intercostal, lumbar arteries), which become the dominant supply inferiorly, similar to the anterior system. | Posterior one-third of the spinal cord |
| Segmental Radicular Arteries | Arise from various systemic arteries along the spine, including deep cervical, ascending cervical, intercostal, lumbar, and lateral sacral arteries. These arteries provide crucial augmentation to the longitudinal spinal arteries, ensuring adequate perfusion along the entire length of the cord, especially below the cervical region. They travel along nerve roots to supply the cord. | All segments of the spinal cord (reinforcing longitudinal flow) |
| Great Anterior Medullary Artery | A major segmental radicular artery, typically arising from a lower intercostal or upper lumbar artery (usually T9-L2). It is the largest single radicular artery and directly reinforces the anterior spinal artery. | Thoracolumbar spinal cord |
Venous Drainage
The venous drainage of the spinal cord largely mirrors its arterial supply. Blood is collected by anterior and posterior spinal veins, which then drain into a network of radicular veins and, ultimately, into the internal vertebral venous plexus. This plexus, in turn, communicates with the external vertebral venous plexus and drains into segmental veins.
