The lumbar spine is made up of the lowest five vertebrae (bones) and the intervening discs (shock absorbers). The vertebrae are the structural components or “building blocks” of the spine. The lumbar vertebrae tend to be much larger than vertebrae in the other parts of the spine. This is a direct result of the lumbar spine having to support much greater loads than the rest of the spine. Though the spinal cord generally ends above the lumbar spine, there is a “sack” of nerves that continues from the spinal cord through the lumbar spine. This nerve sack runs through a large central opening (spinal canal) formed by the vertebrae. Nerves branching from the nerve sack exit the spinal canal through small holes (foramen) directly adjacent to the discs and travel to your legs.

Like the discs in other parts of your spine, discs in your low back are made up of a tough outer “annulus” and a gelatinous “nucleus”. In many ways the structure of a disc may resemble the structure of a “jelly roll”. The nucleus is the well-hydrated, jelly-like, inner portion of the disc that does the majority of the shock absorbing and is contained by the surrounding annulus (the bread portion of the jelly roll). As you age, the nucleus tends to lose water and the annulus may develop cracks. This process, as we will see, may cause problems as one gets older.