Upper Back Physiology Explained

The thoracic spine, which is usually referred to as the upper back or middle back, is very different in form and function to the cervical spine (the neck) or the lumbar spine (the lower back).  We get mobility from the neck and lower back however the thoracic spine is designed to be very stable and strong to allow us to stand upright, additionally, it protects vital organs such as the heart and lungs.

As this section of the spinal column has a great deal of stability and very minimal mobility, there is generally very little risk of degeneration or injury in the upper back over time. Quite possibly the most common factors that cause this type of pain are joint dysfunction and muscular irritation. There could have been an injury to a disc in the upper back such as a thoracic herniated disc or degenerated disc that causes such related back pain, but these injuries are very rare.

The word “thoracic” means related to the chest, and the thoracic spine is the section of the spine that corresponds to the chest area consisting of:

•    Twelve vertebrae in the centre of the spine with ribs attached make up the thoracic spine. When viewed from the side, this section of the spine is slightly concave.
•    Each vertebra in the thoracic spine is attached to a rib on both sides at every level and these in turn meet in the front and connect to the sternum  which is also known as the breastbone. This results in a cage (the thoracic cage) that provides structural protection for the vital organs of the lungs, heart and liver, and also creates a cavity for the lungs to expand and contract.
•    The top nine ribs begin at the spine, curve around and are joined at the front of the chest. As the ribs are firmly attached at the back (the spine) and the front (the sternum), they allow for very limited motion in the spine.
•    The lower three ribs do not join together at the front, but do function to protect the vital organs while allowing for slightly more movement.
•    The joints between the bottom thoracic vertebra (known as T12) and the top lumber vertebra (L1 in the lower back) allow twisting movement from side to side.

As there is very little movement and a great deal of stability throughout the thoracic spine, this section of the back does not usually tend to develop common spinal disorders such as degenerative disc disease, herniated disc, spinal stenosis, or spinal instability. These disorders can cause long-term back pain but are quite rare in the upper back.

Due to this stability and lack of mobility, in most cases anatomic causes of upper back pain cannot be found. An MRI scan or CT scan will seldom image an anatomic problem that is responsive to any sort of surgical solution for the upper back pain. Main causes therefore seem mostly to be either joint dysfunction or muscular irritation and any associated treatment should be based on this diagnosis.