Spinal cord blood supply
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The spinal cord blood supply is a complex arrangement of arterial and venous plexuses.
The spinal cord receives its blood supply by contributions from both longitudinal and reinforced by segmental (aka radiculomedullary) arteries.
Longitudinally, it receives supply from three arteries:
single anterior spinal artery: supplies the anterior two-thirds of the spinal cord
sizable and formed by branches from the intrathecal vertebral arteries
paired posterior spinal arteries: supply the posterior one-third of the spinal cord
small caliber, often appearing discontinuous
Inferiorly the anterior and posterior spinal arteries join as the cruciate anastomosis of the conus medullaris 4.
The anterior and posterior spinal arteries are connected by pial anastomoses called the arterial vasocorona, which encircles the cord and supplies the peripheral lateral aspect of the spinal cord.
The entire blood supply to the cord is reinforced by numerous radiculomedullary or segmental medullary arteries, which from superior to inferior are branches of the following 5:
Branches of these arteries pass through the intervertebral foramina and divide into anterior and posterior radicular, radiculomedullary, or segmental medullary arteries, the latter two of which have variable anastomoses with the anterior and posterior spinal arteries.
The dominant segmental medullary/radiculomedullary artery is called the artery of Adamkiewicz, which can have a variable origin but is typically left-sided and arises between T9 and L2 5. Damage to this vessel can cause paralysis from spinal cord infarction as it is the dominant supplier to the lumbosacral cord segments 5.
In the setting of hypoperfusion, the cord can undergo watershed infarction. As a result of this variable collateral supply, this is variably located but typically in the mid to lower thoracic cord 5.
In the event of arterial supply being interrupted from the aorta (e.g. surgery, trauma) collateral arterial flow can come from the internal thoracic and lateral thoracic arteries, which anastomose with the posterior intercostal arteries.
Venous drainage of the spinal cord
The spinal cord's venous drainage is complex and consists of multiple layers of venous networks. The deeper layers are deep to the dura mater, are closely associated with the spinal cord and include:
intramedullary venous network: centripetally arranged venous network extending to the cord surface
extramedullary venous network
six longitudinal channels organized in a loose-knit plexus
anterior and posterior median longitudinal veins and on each side a pair of longitudinal veins posterior to the nerve roots
These networks demonstrate great variability, and only the anterior spinal vein, which drains the grey matter via sulcal and small plial veins is consistently complete 7.
The radiculomedullary veins link the intramedullary and extramedullary venous plexuses to the vertebral venous plexus. The veins run a similar course to the radiculomedullary arteries, however do not consistently occur in the same segments.
The longitudinal veins drain freely into cerebellar veins and cranial sinuses, and segmentally into medullary veins. The segmental veins drain into the intervertebral veins, and consequently into the external vertebral venous plexus, the caval, and the azygous venous systems 7.
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