Location and Formation
The artery is formed by the fusion of two branches from the right and left vertebral arteries (a. vertebralis). Almost always, it originates from their intradural segment.
After uniting into a single unpaired trunk, the artery descends longitudinally along the anterior surface of the spinal cord. It runs within the anterior median fissure (fissura mediana anterior) and extends along the entire length of the spinal cord down to the filum terminale.
Spinal Cord Blood Supply
The anterior spinal artery forms the anterior arterial territory, supplying the central and anterior portions of the spinal cord parenchyma. Its vascularization zone includes:
- Anterior horns.
- Central gray matter.
- Anterior spinothalamic tract.
- Lateral spinothalamic tract.
- Part of the pyramidal tract — including the lateral corticospinal tract.
- Deep regions of the anterior and lateral funiculi of white matter.
Branches of the Anterior Spinal Artery
Opposite each spinal cord segment, penetrating vessels arise from the main trunk:
- Sulfocommissural (sulcal) arteries (aa. sulcocommissurales) — pass transversely into the median fissure and penetrate the neural tissue. Each such artery supplies strictly one half of the spinal cord segment parenchyma, providing blood to the ventral part of the gray matter.
Contribution to Brainstem Blood Supply
The anterior spinal artery, together with the paramedian branches of the vertebral artery, supplies the medial (paramedian) zone of the medulla oblongata. This zone includes:
- Pyramids.
- Medial lemniscus.
- Medial longitudinal fasciculus.
- Hypoglossal nerve (CN XII) nucleus.
Anastomoses and Vascular Features
The vascular pattern along the entire length of the spinal cord consists of a long chain of anastomoses rather than isolated vessels. Adequate perfusion of the anterior spinal artery is maintained by inflow from numerous segmental arteries; along its course, it anastomoses with anterior radicular arteries.
- Artery of Adamkiewicz (a. radicularis magna) — the largest radicular artery, serving as the main blood source for the lower thoracic, lumbar, and sacral spinal cord segments.
During development, the spinal cord lengthens more slowly than the vertebral column (ascensus medullae spinalis). This creates a topographical mismatch: the entry level of the radicular arteries is higher than their origin from the aorta. Consequently, the radicular arteries take an oblique upward course within the vertebral canal. The artery of Adamkiewicz joins the anterior spinal artery at an acute angle, resembling a hairpin loop. In addition, the anterior and posterior longitudinal major vessels interconnect via radicular anastomoses.
Clinical Significance
Like the brain, the spinal cord is susceptible to arterial or venous ischemia, as well as hemorrhages. The unpaired anterior spinal artery receives collateral flow from numerous segmental arteries.