Arteries of Spinal Cord: Intrinsic Distribution

The central (sulcocommissural) branches of the anterior spinal artery pass back into the anterior median fissure to supply the central parts of the spinal cord. At the anterior commissure, the branches turn alternately right and left to supply the corresponding halves of the cord, except in the lumbar enlargement, where the left and right branches arise from a common trunk. The terminal branches ascend and descend within the cord, supplying overlapping territories. There are 5 to 8 central arteries for each centimeter length of the spinal cord in the cervical region, 2 to 6 in the thoracic region, and 5 to 12 in the lumbosacral area. Branches from each central artery overlap with those from adjacent arteries. The central arteries supply the anterior commissure and adjacent white matter of the anterior columns, anterior horns, bases of the posterior horns, Clarke’s columns, corticospinal tracts, spinothalamic tracts, anterior parts of the gracile and cuneate fasciculi, and the region around the central canal.

The posterior spinal arteries are paired arteries coursing on the posterolateral aspects of the entire length of the spinal cord, although they may become discontinuous at times. Each originates from the intracranial portion of the corresponding vertebral artery, and receives contributions from 10 to 23 posterior radiculomedullary arteries. The posterior spinal arteries distribute blood to the posterior third of their respective sides of the cord.

In the cervicothoracic region, the posterior spinal arteries receive one, and sometimes two, tributaries at each segment. Between the T4 and T8 levels, there are usually two or three posterior radiculomedullary branches, while in the thoracolumbar region, there are several feeders, one of which may be the posterior radicular branch of the artery of Adamkiewicz.

Pial Arterial Plexus. Small pial branches arise from the spinal arteries and ramify and interconnect on the surface of the cord to form a pial plexus. Penetrating branches of the plexus are radially oriented to supply the outer part of the substance of the cord; they follow the principal sulci of the cord (the posterior median sulcus and the posterior intermedian sulcus) to reach the anterior and posterior horns. The peripheral pial branches supply the outer portions of the posterior horns, most of the posterior columns, and the outer portion of the white matter of the periphery of the spinal cord.

There is some degree of overlap in the distribution of the peripheral and central arteries at the capillary level, but they do not anastomose at the arterial level, and hence both types are, in effect, end arteries.

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