Sometimes a weak spot develops in the disc and a portion of the inner disc pushes out into the spinal canal where the large nerves are located. These large nerves are very sensitive to the disc material and, when irritated, can inflame the surrounding tissues, which then irritates the nerve even more. Additionally, the periphery of the disc has many small nerves that are sensitive to chemical change within the disc and can create the perception of pain. In addition to bone and discs, many types of soft tissue support the spinal column. These structures have a good blood supply and will heal after an injury.
Muscles are quite resilient structures and are the least likely to be torn or injured.
When they are injured, muscles have excellent blood supply and the blood brings the necessary nutrients to enable the muscles to quickly repair themselves. While the muscles themselves are rarely the source of long-term back pain, they do contribute to it. Weak muscles place more stress on the other structures in the spine and this in turn can lead to another episode of pain. Muscles can also contribute to back pain through tension. Emotions such as stress, anxiety and anger can lead to tense muscles.