• L5 vertebra consists of a vertebral body in the front and an arch in the back that has 3 bony protrusions: one prominent spinous process in the middle and two transverse processes on either side.
  • L5-S1 intervertebral disc provides cushioning and shock-absorbing functions to protect L5 and S1 vertebrae during spinal movements.
  • L5 spinal nerve roots join with other nerves to form bigger nerves that extend down the spine and travel down each leg.
  • S1 vertebra, also called the sacral base, is the wide upper end of the triangle-shaped sacrum.

Common Problems

  • Disc problems. A steeper inclination of the L5-S1 disc leads to a higher degree of shear stresses and increases the risk disc of injury and degeneration.
  • Facet joint pain. The lumbosacral joint may develop wear-and-tear arthritis (osteoarthritis) over time due to its high load-bearing function.
  • Spondylolysis. The L5 vertebra is susceptible to spondylolysis, which is a fracture of the pars interarticularis most commonly due to repetitive stress on the bone.
  • Spondylolisthesis. If the pars of L5 fractures on both sides, the vertebra may slip over S1 in a condition called spondylolisthesis.

Common Symptoms and Signs

  • Pain, felt as a sharp, shooting, and/or searing feeling in the buttock, thigh, leg, foot, and/or toes
  • Numbness in the foot and/or toes Weakness in the leg and/or foot muscles and an inability to lift the foot off the floor