There are several potential sources and causes of back pain. However, the diagnosis of specific tissues of the spine as the cause of pain presents problems. This is because symptoms arising from different spinal tissues can feel very similar and is difficult to differentiate without the use of invasive diagnostic intervention procedures, such as local anesthetic blocks.
One potential source of back pain is skeletal muscle of the back. Potential causes of pain in muscle tissue include Muscle strains (pulled muscles), muscle spasm, and muscle imbalances. However, imaging studies do not support the notion of muscle tissue damage in many back pain cases, and the neurophysiology of muscle spasm and muscle imbalances are not well understood.

The muscles in your shoulder are connected to your arm by tendons. Between the tendons and bones are small sacs of fluid called bursa. They lubricate the shoulder so it moves easily. Continual stress on your shoulder can cause the bursa to get squeezed, swollen, stiff, and inflamed (
bursitis). Bursitis can make it painful, or even impossible, to raise your arm. Image Credit: CDC

If you bend forward over and over for months or years, the discs are weakened, which may lead to disc rupture (or "herniation"). Image Credit: CDC
Another potential source of low back pain is the synovial joints of the spine (e.g. zygapophysial joints). These have been identified as the primary source of the pain in approximately one third of people with chronic low back pain, and in most people with neck pain following whiplash.
Further Reading
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