Costovertebral (rib) joints are starting to be recognised as a source of pain.
Mid-back pain is often misdiagnosed as either spinal (vertebral) pain or muscular pain. The figure below depicts pain referral patterns of various costovertebral joints – where the rib head joins the spine. This is a joint that when subluxated can induce its own pain patterns.
Reference:
Young, B.A., et al., Thoracic costotransverse joint pain patterns: a study in normal volunteers. BMC Musculoskelet Disord., 2008. 9 (1): p140.