Anterior Spinal ArteryEdit
The anterior spinal artery (ASA) is a central component of the spinal cord’s vascular system. It runs along the ventral (front) surface of the spinal cord and is primarily responsible for perfusing the anterior two-thirds of the cord, including the motor pathways and much of the sensory pathways. The ASA is typically formed by branches that arise from the vertebral arteries and is reinforced by segmental medullary arteries as it travels, creating a dynamic network that helps protect the cord from ischemia in one region by collateral flow from others. Its performance is essential for voluntary movement, pain and temperature sensation, and autonomic control in the regions it supplies. For a broader view of the surrounding structures, researchers and clinicians often consider the ASA in the context of the broader cerebrospinal circulation and spinal cord perfusion spinal cord.
Anatomic and vascular features of the ASA are described in relation to its origin, course, and the territories it covers. The artery typically originates near the junction of the two vertebral arteries in the brainstem region and then descends along the anterior median fissure of the spinal cord, where it forms a midline channel that supplies the anterior horn cells, corticospinal tracts, and spinothalamic tracts. Along its course, it is reinforced by multiple segmental radiculomedullary arteries that arise from nearby arteries such as the intercostal and lumbar arteries; the most notable of these is the great radicular artery of Adamkiewicz (arteria radicularis magna), which provides a major inflow to the lower thoracic and upper lumbar cord. These relationships are central to understanding how the ASA maintains perfusion across different spinal levels and how injury or disease can alter cord function Adamkiewicz artery; radiculomedullary arteries.
Anatomy and Blood Supply
Origin and course
The ASA is usually disclosed as a single ventral spinal artery that lies in the anterior median fissure of the spinal cord. Its formation is intimately tied to the convergence of longitudinal channels that originate from the vertebral arteries and nearby feeders. In many individuals, the ASA receives additional supply from radiculomedullary arteries that enter the cord with the anterior nerve roots. The balance of flow and redundancy varies among people, which explains some regional differences in susceptibility to ischemia under stress or injury vertebral artery; spinal cord.
Reinforcement and major contributors
Segmental inputs are a critical feature of spinal cord perfusion. The great radicular artery of Adamkiewicz is the most frequently cited source of substantial reinforcement for the lower thoracic and upper lumbar cord, but multiple smaller radiculomedullary arteries contribute across the cervical and thoracic regions. The anterior spinal artery interacts with the posterior spinal arteries to create perfusion patterns that help protect the cord, though the ASA remains the primary supplier of the anterior two-thirds of the cord. Understanding these connections is important for interpreting imaging findings and planning surgical approaches near the spinal column posterior spinal artery; radiculomedullary arteries.
Territories supplied
The ASA supplies the anterior two-thirds of the spinal cord, including the anterior horns (motor neurons), most of the corticospinal tracts, and the spinothalamic tracts, as well as autonomic pathways that influence bladder and bowel function in certain levels. The posterior one-third of the cord is primarily supplied by the posterior spinal arteries, which creates a division of labor within the spinal cord’s vascular bed. This arrangement helps explain the classic clinical syndrome that can arise when the ASA is compromised, while posterior column pathways may remain at least partially intact if only the ASA is affected spinal cord; corticospinal tract; spinothalamic tract; posterior spinal artery.
Variation and collateral circulation
Anatomic variation is common in the ASA and its reinforcement network. In some individuals, the pattern of segmental inputs is asymmetric or more robust in certain regions, reflecting the variable anatomy of the radiculomedullary supply. Collateral circulation can mitigate focal ischemia, but it can also be overwhelmed in cases of rapid arterial occlusion or complex trauma. Clinicians rely on this knowledge when interpreting imaging studies such as magnetic resonance imaging or vascular studies of the spine, particularly in patients with acute myelopathy or suspected spinal vascular compromise radiculomedullary arteries.
Clinical Significance
Anterior spinal artery syndrome
Occlusion or severe hypoperfusion of the ASA leads to a characteristic syndrome, often described as anterior spinal artery syndrome. Since the ASA supplies the motor tracts and the spinothalamic pathways, patients typically present with bilateral paralysis or weakness below the level of the lesion and loss of pain and temperature sensation in the same distribution, while vibration and proprioception (carried by the dorsal columns) may be preserved or less affected. Autonomic dysfunction can occur, reflecting disruption of autonomic pathways within the cord. The exact presentation depends on the level and extent of the vascular compromise, and it can result from a range of etiologies, including thrombosis, dissection, trauma, or compressive processes that affect the feeding arteries spinal cord; corticospinal tract; spinothalamic tract.
Vascular lesions and iatrogenic injury
Vascular lesions involving the ASA can arise from atherosclerotic disease, vasculitis, or trauma, and iatrogenic injury during surgical procedures of the spine or neck can inadvertently compromise the artery’s flow. Surgeons and interventional radiologists emphasize preserving ASA perfusion when planning decompression surgeries, spinal fusions, or endovascular interventions in the vertebral and spinal regions. In some cases, understanding ASA anatomy helps predict outcomes and guide postoperative management in patients with spinal cord symptoms spinal cord injury; neurosurgery.
Imaging and diagnosis
Modern imaging techniques, including MRI and CT angiography, are used to assess ASA patency and spinal cord perfusion in suspected cases of anterior spinal artery compromise. Characteristic findings on MRI may include diffusion abnormalities in the anterior two-thirds of the cord, reflecting ischemia, with relative preservation of dorsal column signaling. Clinicians correlate imaging with clinical exam to determine the level of vascular involvement and to identify potential causes such as dissection or vascular anomaly magnetic resonance imaging; ischemia.
Development and Research
The development of the spinal vasculature involves complex embryologic processes that establish longitudinal arterial channels and segmental reinforcements. Ongoing research in vascular neuroscience and spinal surgery continues to elucidate the variability of the ASA’s anatomy, the impact of collateral networks, and the best strategies to protect cord perfusion during medical and surgical interventions. Clinicians and researchers reference the broader literature on cerebrovascular anatomy to understand how spinal arterial supply integrates with overall central nervous system blood flow cerebral circulation; vertebral artery.