Spinal cord blood supply

The spinal cord blood supply is formed by many different vessels with an extensive collateral supplya complex arrangement of arterial and drainagevenous plexuses.

Arterial supply

The spinal cord is suppliedreceives its blood supply by threecontributions 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

  • sizeable and formed by branches from the intrathecal vertebral arteries

• paired posterior spinal arteries: supply the posterior one-third of the spinal cord

  • small calibre, 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:

• posterior inferior cerebellar arteries

• vertebral arteries

• ascending cervical arteries

• deep cervical arteries

• posterior intercostal arteries

• subcostal arteries

• lumbar arteries

• lateral sacral arteries

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 (and vertebrae)

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 organised 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. TheseThe veins run a similar course to the radiculomedullary arteries, however do not consistently occur in the same segments.

The vertebral venous plexus is the more superficial venous network and is located superficial to the dura mater, extending from the foramen magnum to the sacral hiatus. It consists of three interconnected divisions:

• internal vertebral venous plexus 

  • consists of anterior and posterior internal vertebral venous plexus in the epidural space 

    • anterior internal epidural plexus 

      • two anterior interconnecting longitudinal vessels 

      • more prominent, lies posterior to the vertebral bodies 

    • posterior internal epidural plexus 

      • two posterior interconnecting longitudinal vessels

      • less prominent - lies anterior to the lamina 

  • segmentally receives drainage from radiculomedullaryveins drain freely into cerebellar veins and basivertebralcranial sinuses, and segmentally into medullary veins. The segmental veins drain into the intervertebral veins, and also Batson venous plexus 

  • communicates above with occipital and basilar sinuses

  • drains into intervertebral veins then to vertebral, intercostal, lumbar, lateral sacral veins

• external vertebral venous plexus

  • in communication with the internal vertebral venous plexus and basivertebral veins via the intervertebral veins which run through the intervertebral foramina

  • consists of anterior (anterior to the vertebral bodies) and posterior (posterior to the ligamentum flavum) external vertebral venous plexuses surrounding the vertebral column

  • drains into cervical, azygos, ascending lumbar and lateral sacral 

• basivertebral veins

  • runs horizontally within vertebral bodies 

  • receives drainage from numerous small venous channels

  • drainsconsequently into the anterior external vertebral venous plexus (anteriorly), the caval, and anterior internal vertebralthe azygous venous plexus (posteriorly)systems ⁷.

Related pathology

• acute spinal cord ischaemia syndrome

• anterior spinal artery syndrome

• posterior spinal artery syndrome

• fibrocartilaginous embolism