Soft tissues are muscles, tendons (connections from muscle to bone), ligaments (connections from bone to bone), and intervertebral disks (cushions between the bones of the spine).
Things like trauma, fall, sudden stretching of a contracted muscle (lifting) or repeated activity/exposure may produce pressure, pinching, cutting, tearing, vibrating, loading, twisting, or stretching that may result in damage/tearing of soft tissues. Damage, resulting in small amounts of cell death, produces inflammation which irritates nerve endings, causing pain. Additionally, when soft tissues suffer either acute or repetitive injury, there is a disruption in blood flow the local tissue. Since blood supplies food and oxygen to all cells, injury is associated with a local “energy crisis” in the cells/tissues. In muscle, energy from blood is needed to both “link up” muscle fibers to create contraction, and to “unlink” muscle fibers for muscle relaxation. When there is decreased blood flow, contracting muscle fibers may fail to “unlink” and prolonged contraction (spasm) may ensue. This prolonged contraction, in turn, slightly crushes blood flow to the same area of affected muscle, exacerbating the problem. According to Travell and Simmons, this how trigger points form. Muscles with trigger points—the tight knots and bands that may be found in muscles, including those of the low back—are often abnormally shortened, with the increased tone and tension associated with spasm.
For more about trigger points and muscle spasm, click here.
In the in the back and in spine, there also tendons (connections between muscle and bone) and ligaments (connections from bone to bone). Injury or tears (large or small) to tendons or ligaments can produce the same appropriate or inappropriate inflammation and or/pain signaling to the brain. Scar tissue, the result of inflammation, may tighten or loosen tendons or ligaments. The low back needs to remain upright, against gravity, and therefore needs support. Tendons and ligaments are part of the low back’s support system. If tendons and ligaments loosen or tear, the back may lose needed support. This instability then allows gravity to worsen the wear and tear forces on the low back, thus increasing inflammation and/or pain.
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