To understand back pain, one must first consider how the spinal cord is designed. It extends from the base of your neck to the lumbar region. The spinal cord is gently curved and is meant to remain in this position. When you sit down, the muscles and ligaments that support the vertebrae are stretched. If you sit for a long time the ligaments are lengthened and strained. The orthopedic term for this is, creep. This is ironical because the pain that it causes also creeps in.