Anatomy of the posterolateral disc region.

Eighteen cadaveric dissections were performed to determine the location of the segmental vessels and the cephalad nerve root in relation to the posterolateral lumbar disc. The most lateral point of each lumbar disc was determined, and measurements were made form this reference point. Segmental vessels were found to be a mean of 10 to 13 mm from the junction of the vertebral body and the disc. The exception to this was the vessel superior to L5-S1, which was a mean of 7 mm from the disc margin. The cephalad nerve roots were consistently found to be adjacent to the disc, and were an average of 9 to 22 mm posterior to the lateral reference point.