Middle back pain can have several causes, including impact trauma, arthritis, herniated discs, muscle strains, scoliosis, poor posture, and many more. The term 'middle back' often refers to the thoracic spine — the region of the back between the rib cage and the base of the neck. - Your thoracic spine is the middle section of your vertebra between your neck and lower back and composes 12 thoracic vertebras and your rib cage. Thoracic mobility involves available movement of this portion of the sp