Chronic back pain is measured by duration and is defined as pain that persists for more than 3 months. It is often progressive and the specific cause can be difficult to determine.
The back is made of bones, muscles and tissues that form the posterior part of the body's trunk from the neck to the pelvis. The centerpiece is the spinal column, which not only supports the upper body's weight but houses and protects the spinal cord, which is the delicate nervous system structure that carries signals that control the body's movements and convey its sensations.
Stacked on top of one another are more than 30 bones, called vertebrae that form the spinal column. Each of these bones contains a round-shaped hole that when stacked on top of one another, creates a channel that surrounds the spinal cord. The cord descends from the base of the brain and extends to just below the rib cage. Small nerve roots enter and emerge from the spinal cord through spaces between the vertebrae. The spaces between the vertebrae are maintained by round, spongy pads of cartilage called intervertebral discs that allow for flexibility in the lower back and act much like shock absorbers throughout the spinal column to cushion the bones as the body moves. Bands of tissue known as ligaments and tendons hold the vertebrae in place and attach the muscles to the spinal column.
The spine has 4 regions: