Arterial supply of the spinal cord

Regarding the arterial supply of the spinal cord, the following statements are true

EXCEPT which one?

a) There are two posterior spinal arteries and one anterior spinal artery, all derived

from the vertebral arteries

b) The great anterior radicular artery (spinal artery of Adamkiewicz) most often arises

at T10 on the left

c) Some radicular arteries derive their supply from intercostal arteries

d) The pia mater does not cover the spinal vasculature

e) The anterior inferior spinal cord is more vulnerable to ischaemia than the posterior

cord

Answer: d

Explanation

The anterior spinal artery is unpaired, being formed by a branch from each vertebral

artery anastomosing at the level of the foramen magnum. The two posterior spinal

arteries are variably described as originating from the vertebral arteries or sometimes

via the posterior inferior cerebellar arteries. These are branches of the vertebral arteries

so Option (a) remains correct. These three arteries run the length of the spinal cord,

augmented in a segmental fashion by radicular arteries at most (usually 21) spinal

levels. The origin of the radicular arteries depends on the vertebral level at which

they contribute to the anterior and posterior spinal arteries, thus they are derived

from the vertebral, deep cervical, intercostal and lumbar arteries. Those radicular

arteries that do not contribute to the longitudinal arteries directly supply the cord at

that level. Posteriorly, a dense plexus of arterial anastomoses confer more reliable

supply of oxygenated blood. Anteriorly, the single spinal artery means occlusion or

hypoperfusion risks ischaemia. One radicular artery dominates supply to the inferior

two thirds of the cord. This is known as the radicularis magna, great anterior

radicular artery or spinal artery of Adamkiewicz. Aortic or spinal surgery or traumatic

spinal cord injury may disrupt this supply with the consequence of flaccid

paraplegia and symmetrical loss of pain and temperature perception below the level

of the ischaemia, as these pathways run in the anterior part of the cord. The great

anterior radicular artery arises in the lower thoracic or upper lumbar levels, but with

greatest frequency arises on the left at T10. The pia mater is closely adherent to the

substance of the cord, but does cover the spinal vessels and ensheathes the anterior

spinal artery.