Posterior radicular artery

The posterior radicular artery is a segmental blood vessel that accompanies the posterior (dorsal) nerve root as it enters the spinal canal through the intervertebral foramen. These arteries arise from segmental vessels including the vertebral, ascending cervical, deep cervical, intercostal, lumbar, and sacral arteries and travel along the dorsal nerve roots to supply the posterior spinal cord and its surrounding structures.

Key anatomical and functional features:

• Course: Posterior radicular arteries enter the spinal canal via the intervertebral foramina alongside the dorsal nerve roots. They run along the surface of the posterior nerve rootlets toward the posterolateral aspect of the spinal cord.

• Contribution to the posterior spinal arteries: Select posterior radicular arteries typically larger ones present at variable segmental levels anastomose with the paired posterior spinal arteries (also called posterolateral spinal arteries), which run longitudinally along the dorsolateral surface of the spinal cord near the dorsal root entry zone. These posterior spinal arteries form a less well-defined plexiform network (the "pial plexus") compared to the single anterior spinal artery.

• Number and distribution: Posterior radicular arteries are more numerous than anterior radicular arteries, with approximately 10-23 posterior radicular arteries present along the length of the spinal cord, though the exact number and segmental levels vary between individuals.

• Territory of supply: They contribute to the blood supply of the posterior one-third of the spinal cord, including the posterior columns (dorsal columns), the posterior horns of the gray matter, and the surface of the posterior spinal cord.

• Distinction from the anterior radicular artery: The anterior radicular artery accompanies the ventral nerve root and feeds the anterior spinal artery. The largest anterior radicular artery is the artery of Adamkiewicz (arteria radicularis magna), which is the dominant blood supply to the lower two-thirds of the anterior spinal cord. There is no single dominant posterior radicular artery equivalent to the artery of Adamkiewicz, as the posterior spinal circulation is supplied by multiple, more evenly distributed posterior radicular feeders.

• Clinical significance: Compromise of posterior radicular arteries for example, during spinal surgery, aortic procedures, or due to vascular disease can contribute to posterior spinal cord ischemia, which may manifest as loss of proprioception, vibration sense, and fine touch (posterior column syndrome), though isolated posterior cord infarction is rare compared to anterior cord syndrome.