L5-S1 is the exact spot where the lumbar spine ends and the sacral spine begins. The lumbosacral joint connects these bones.

Methods A total of 116 patients referred with symptoms of lumbar ... % CI 1.06–37.21) for L4, 1.74 (95% CI 1.04–2.93) for L5, and 1.29 (95% CI 0.97–1.72) for S1 nerve root impingement.

These are not uncommon symptoms that can occur for ... Sciatica occurs when the nerve roots that form the sciatic nerve, L4, ...