Your back consists of stacked bones called vertebrae. There are discs between the vertebrae that act as shock absorbers, allow the spine to bend and help protect the spinal cord. Each disc consist of a soft sermi-fluid center (nucleus) that is surrounded and held together by strong ligaments.
The discs in your back can be the source of a great deal of pain. This pain can range from a nagging ache and sciatic discomfort to excruciating pain that incapacitates you. There are simple measures you can take to reduce the risk of disc problems occurring and to reduce your pain once problems do occur.
To understand how disc pain happens, it is important to understand normal posture. When standing upright, there is a natural inward curve in the lower back called a lumbar lordosis. With natural lordosis, your body weight is distributed evenly over the discs. This lordosis is lost whenever you slouch or bend forward. Back problems develop if you find yourself in these positions for long periods of time. This occurs because the vertebrae are placed in a position that pushes the nucleus backwards and stresses the ligaments at the back of the disc.
If pressure on the ligaments is severe enough, they may become weak and allow the soft inside part of the disc to bulge outward (prolapse) and press on the spinal nerves. This can cause sciatic nerve pain in the buttocks or down the leg.
The disc, which sits between two vertebrae, acts like a shock absorber for the spine. Nerves come out of spinal cord and pass through small holes behind the disc.