Arteries of Spinal Cord

Description

The arterial supply of the spinal cord is via longitudinal and segmental distributions.

The longitudinal supply is via the anterior and posterior spinal arteries that extend from their intracranial origin to their termination at the conus medullaris of the spinal cord. The segmental distribution is via the radicular arteries.

The anterior spinal artery arises from the union of the anterior spinal branches of the vertebral arteries. It descends in median fissure of the spinal cord and supplies the anterior two thirds of the cross-sectional area of the spinal cord (Standring, 2020).

The posterior spinal arteries (two in number) arise either directly from the vertebral artery or from the posterior inferior cerebellar artery (a branch of the vertebral artery) and descend in posterolateral sulci of the spinal cord. The posterior spinal arteries supply the posterior one third of the spinal cord.

The anterior and posterior spinal arteries cannot supply the spinal cord alone and heavily depend on segmental contributions from the radicular arteries. These arteries are derived from the spinal branches of the vertebral, ascending cervical, intercostal, and lumbar arteries. They enter the vertebral canal via the intervertebral foramina and accompany the anterior and posterior roots of the spinal cord.

The small anterior and posterior radicular arteries supply the anterior and posterior roots of the spinal cord. They tend not to reach all the way to the anterior or posterior spinal arteries, but may terminate in the pial plexus (Standring, 2020). However, at varying intervals, particularly at the cervical and lumbosacral enlargements, the radicular arteries are larger. These are termed the segmental medullary, or radiculomedullary, arteries. The anterior and posterior segmental medullary arteries anastomose with the anterior and posterior spinal arteries, respectively.

The largest segmental medullary artery is the great radicular artery (or great segmental medullary of Adamkiewicz), which variably arises from a spinal branch of the lower posterior intercostal arteries (T9-T11), the subcostal artery (T12), or from the upper lumbar arteries (L1 or L2). It arises on the left side in 65% of individuals and is responsible for reinforcing arterial supply to the spinal cord (Moore, Dalley and Agur, 2013).

The cauda equina is supplied by spinal branches from the lumbar, iliolumbar, and lateral and median sacral arteries. These branches ascend to the conus medullaris of the spinal cord to form an anastomotic arterial arch.