Lateral sacral arteries
The lateral sacral arteries are among the arteries of the lower back. They have spinal branches, which supply blood to the sacral nerve rootlets, adjacent muscles, meninges, and sacrum. These arteries traverse the sacrum's lateral border.
There are two lateral sacral arteries on each side of the internal iliac artery: these are the superior and inferior arteries. The lateral sacral arteries, along with the iliolumbar and the superior gluteal arteries, are branches of the posterior division of the internal iliac artery.
The superior lateral sacral artery passes down and across the sacrum before it connects with branches of the middle sacral arteries and then the anterior sacral foramen to supply the membranes. It then emerges at the upper posterior sacral foramen, supplying blood to the skin and muscles over the sacrum.
The inferior lateral sacral artery runs crosswise in front of the piriformis and sacral nerves before descending in front of the sacrum and connects with the middle sacral and superior lateral sacral artery.