What are some causes of an ache in the middle of the back?

The causes of an ache in the middle of the back include irritation or inflammation of the middle back structures and conditions such as a herniated disc, according to Healthgrades. Conditions such as osteoarthritis, osteoporosis, spinal stenosis, spinal degeneration and Paget's disease may also cause middle back pain.

The irritation or inflammation of the middle back structures, including tendons, muscles, discs, thoracic spine and ligaments, occurs when an individual moves suddenly during strenuous activities, and commonly attacks individuals who live sedentary lives, notes Healthgrades. A herniated disc causes pain in the middle of the back by exerting pressure against the spinal nerve roots.