The thoracic spine, also known as the upper back or middle back, consists of 12 vertebrae (T1-T12), each of which provides a base for a pair of ribs. The vertebrae in this area of the spine grow larger as you move down the back.
Mobility in the thoracic spine is limited because of the ribs. The relatively small range of motion, as compared to the cervical spine and the lumbar spine, is one of the main reasons wear-and-tear spinal conditions like bulging discs are less common within the thoracic spine.
The structure of the T1-T8 vertebrae includes a prominent spinous process, which accounts for the knobs you feel through the skin in the center of your back. This bony extension angles downward along most of the thoracic spine, and then begins to grow smaller and level off at the T9-T12. In addition to providing skeletal support for the midsection, the middle spine houses 12 thoracic nerve roots, which send sensory impulses to these areas of the body:
While nerve compression within the thoracic spine is not as common as in other spinal segments, the intervertebral discs in the T1-T12 are subject to the same type of degenerative conditions that affect the cervical and lumbar spine, including osteoarthritis and degenerative disc disease. This can cause chronic back pain and adversely affect your quality of life.