Anterior spinal artery

At a glance

English

Anterior spinal artery

Latin (TA2)

Arteria spinalis anterior

System

Artery

Region

Head

Side

Paired, left and right

About the anterior spinal artery

This is the long vessel that lies along the front of the spinal cord. It begins inside the skull as a pair of small twigs, one from each vertebral artery shortly before the two vertebrals join to form the basilar artery. The two twigs are often unequal in size. They run down and medially over the front of the medulla and unite near the foramen magnum into one midline trunk.

That trunk descends the whole length of the cord in the pia mater, lying at the entrance to the anterior median fissure. Below the conus medullaris it continues as a fine thread along the filum terminale, and near its lower end gives branches to the cauda equina.

A vessel this long and slender cannot carry enough blood from the head alone. It is fed at intervals by anterior segmental medullary (radicular) arteries that pass into the spinal canal by way of the intervertebral foramina. In the neck these come from the vertebral and ascending cervical arteries, in the thorax from the posterior intercostal arteries, and lower down from the lumbar, iliolumbar and lateral sacral arteries. The largest is the great anterior segmental medullary artery, the artery of Adamkiewicz, which usually enters on the left in the lower thoracic or upper lumbar region and supplies most of the lower cord.

Through its sulcal branches it supplies roughly the anterior two-thirds of the cord, including the anterior grey horns and the corticospinal and spinothalamic tracts. Blockage therefore causes the anterior spinal artery syndrome: paralysis below the level and loss of pain and temperature sense on both sides, with touch and joint position sense preserved by the dorsal columns. When the blockage lies higher, on the medulla itself, the result is instead the medial medullary syndrome.

Course and supply

Arises from

Two small branches from the terminal parts of the vertebral arteries, uniting near the foramen magnum.

Ends in

Descends the length of the spinal cord and ends as a fine thread along the filum terminale, with branches to the cauda equina.

Supplies

Supplies the pia mater and roughly the anterior two-thirds of the spinal cord and lower medulla, including the anterior horns and the corticospinal and spinothalamic tracts.