This area is known as the cervicothoracic junction, or CT junction. In this area of the spine a highly flexible neck (cervical spine) transitions to a much more inflexible upper back. Also, the curvature of the spine changes from a backward curve in the neck (lordosis) to a forward curve in the thoracic spine (kyphosis). These factors can lead to increased stress at the CT junction while stationary and with movement.
Regular chiropractic adjustments as well as maintaining good upper back and shoulder mobility can prevent pain in the CT junction.