Posterior spinal branch of posterior inferior cerebellar artery

The posterior spinal artery (PSA) may arise from PICA, although this is a variable arrangement rather than a constant branch of PICA. When arising from PICA, it descends toward the upper cervical spinal cord and contributes to the posterior spinal arterial circulation, supplying the posterior aspect of the upper spinal cord and giving branches that participate in the vascular supply around the caudal medulla.