ADD-ONS / ANATOMY
Blood Supply of the Spinal Cord
Created 04/03/2022, last revision 24/05/2023
The arterial system
Spinal arteries
- the spinal arteries originate primarily from the vertebral arteries and run longitudinally from the medulla of the brainstem to the medullary cone
- the VAs are the primary source of blood to the upper spinal cord
- anterior spinal artery (ASA) runs along the anterior median fissure and gives off many branches to the median fissure (sulcocommissural and circumferential branches)
- common trunk arising from both VAs with a predominance of one ramus over the other or with a single unilateral ramus
- ASA supplies the anterior 2/3 of the spinal cord
- ASA may not be continuous (typically in the mid-thoracic segment)
- ASA communicates sporadically with the posterior spinal arteries via a pial plexus (vasocorona); at most levels, it gives off a sulcal artery that enters the anterior median fissure.
- ischemic injury to this vessel results in dysfunction of the corticospinal, lateral spinothalamic, and autonomic intermedial pathways
- common trunk arising from both VAs with a predominance of one ramus over the other or with a single unilateral ramus
- pair of posterior spinal arteries run (one on each side of the midline) along the posterolateral sulcus and supply the posterior spinal cord horns and posterior column
- they have numerous anastomoses and form a plexiform system (vasocorona)
- they have numerous anastomoses and form a plexiform system (vasocorona)
- there is an overlap and redundancy between the terminal supply branches of these two systems within the parenchyma of the spinal cord itself
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Segmental medullary arteries
- of the multiple fetal segmental arteries, only 6-14 large arteries persist in adulthood
- they originate from the spinal branches of the ascending cervical, deep cervical, posterior intercostal, and lumbosacral arteries (from the aortic arch, thoracic and abdominal aorta)
- they enter the spinal canal through the intervertebral foramina and accompany the roots
- they are often unpaired and feed the spinal arteries at different levels
- they originate from the spinal branches of the ascending cervical, deep cervical, posterior intercostal, and lumbosacral arteries (from the aortic arch, thoracic and abdominal aorta)
- segmental arteries reinforce the anterior and posterior spinal arteries providing additional vascularization of the spinal cord in lower segments (blood from the vertebral arteries can only supply the upper portion of the spinal cord, the circulation of the rest of the spinal cord depends on the segmental arteries )
- segmental medullary arteries
- the larger vessels that, after supplying dorsal or ventral root, anastomose with the spinal arteries (Greathouse, 2001)
- dorsal and ventral radicular arteries
- most radicular arteries are small and supply only the nerve roots; they rarely reach the anterior or posterior spinal arteries (Greathouse, 2001)
- segmental medullary arteries
- in the cervical region, the segmental medullary arteries are usually distributed bilaterally; in the thoracic and lumbar regions, they are mainly left-sided
- C1-Th3 segment – from VA (C1-C6), ascending cervical artery (C3-4), and deep cervical artery (C3–C7)
- in the cervical region, the radiculomedullary artery from C4–C7 is usually the most predominant and is called the artery of cervical enlargement (Zhang, 2021)
- in the cervical region, the radiculomedullary artery from C4–C7 is usually the most predominant and is called the artery of cervical enlargement (Zhang, 2021)
- Th segment – from posterior intercostal arteries
- a major segmental feeder may occur in the upper thoracic spine, often at the level of the Th5 – artery of von Haller
- Th8-conus – artery of Adamkiewicz and branches from iliolumbar arteries
- artery of Adamkiewicz is the largest of the segmental arteries (level T9-Th12 in 62%)
- C1-Th3 segment – from VA (C1-C6), ascending cervical artery (C3-4), and deep cervical artery (C3–C7)
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- damage to one segmental artery in a critical area (e.g., in aortic dissection) or damage to multiple segmental arteries (e.g., after aortic surgery) can lead to the spinal cord infarction
- segmental arteries supply the vertebral bodies, meninges, and spinal cord (therefore, in spinal cord infarction, the infarct is often seen in the vertebral body)
- the anterior spinal artery (ASA) region is more vulnerable to ischemia than the posterior third because it has fewer anastomoses. On the surface of the spinal cord, the junctions of the segmental arteries with the posterior and anterior spinal arteries form a closed circulatory system (called the arterial vasocorona)
- the most vulnerable areas include the upper thoracic segments (Th1-4) and the lumbar intumescence (especially the first lumbar segment)
- this area is supplied by the most constant and largest segmental artery, the Adamkiewicz artery (also known as the lumbar intumescent artery)
- the Adamkiewicz artery usually enters the spinal canal at the segment Th9-L1, often on the left side
The venous system
- small intramedullary veins drain into the longitudinal tortuous venous plexus, that forms along the entire length of the spinal cord
- ventral sulcal veins drain the medial portion of the anterior horn, the anterior commissure, and the white matter of the anterior funiculus
- the dorsal central veins drain the gray commissure and the white matter near the posterior median sulcus
- the remaining areas of the spinal cord are also drained centrifugally by peripheral radial veins
- anastomotic veins connect the radial and sulcal veins
- this plexus is formed by:
- anterior spinal vein (collects blood from the sulcal and radial veins) – usually paired in the cervical and thoracic regions, a single vessel in the lumbar segment
- posterior spinal vein and 2 lateral longitudinal veins that pass behind the nerve roots
- venous vasocorona (connecting longitudinal trunks)
- from both the anterior and posterior veins, blood is drained to the internal vertebral venous plexus (the Batson venous plexus) via several ventral and dorsal radiculomedullary veins
- radiculomedullary veins exit the dura, usually along the nerve root
- the largest radiculomedullary vein called the great anterior radiculomedullary vein (GARV), drains the thoracolumbar cord and may be mistaken for the artery of Adamkiewicz
- the internal vertebral plexus consists of two anterior longitudinal veins running on either side of the posterior longitudinal ligament and two posterior veins running anterior to the ligamentum flavum
- the internal vertebral plexus is connected to the external vertebral plexus via the intervertebral foramina (intervertebral veins)
- veins around the spine are not equipped with valves, and blood can flow in different directions depending on the pressure gradient
- the external vertebral plexus drains into the vertebral veins of the neck and the segmental veins of the trunk
- cervical cord → vertebral, deep cervical, and jugular veins
- thoracic cord → left hemiazygos and accessory hemiazygos veins and right azygos vein
- lumbar cord → azygos and ascending lumbar veins
