The spine in the upper back and abdomen is known as the thoracic spine. It is one of three sections of the spinal column. The thoracic spine sits between the cervical spine in the neck and the lumbar spine in the lower back.

All three sections make a tower of 24 bones that gives the body structure and houses the spinal cord. The spinal cord and its nerves facilitate communication between the body and the brain. Together, the brain and spinal cord make up the central nervous system.

Other than protecting the spinal cord, the vertebrae create joints that allow the spine to bend and twist. The joints of the thoracic spine are important to arm movement, bending over, and other movements.

Several muscles connected to vertebrae via ligaments, or flexible bands of fibrous tissue, move the spine. The muscles of the back fit into the grooves of the spinous process, or the protrusion of the vertebra than can be felt through parts of the skin in the neck.

The muscles that affect the thoracic spine’s function include:

• Spinalis: This long muscle moves the spine and helps with posture. Ligaments of this muscle attach to multiple thoracic vertebrae. Although narrow at its ends, at the top of the first thoracic vertebra and within the lumbar spine, the spinalis is wide in the middle.
• Longissimus: Another long muscle, this one travels up the spine from the middle of the lumbar spine. It runs on both sides of the spinalis.

The space between each vertebra contains an intervertebral disc made of cushioning material that connects the vertebrae to one another and pads these joints.

The thoracic spine is unique in relation to other areas of the spine because pairs of rib bones extend from the spaces between its 12 vertebrae. The ribs’ curved shapes create a cage-like structure that houses and protects many vital organs, including the heart and lungs.

Because the thoracic spine is used so much in daily life, it is prone to strain and injury for many reasons, from improper posture to compression fracture. Some injuries can put pressure on the spinal nerves, creating even stronger pain and other symptoms. Some causes of reoccurring back pain include:

• Muscle injury, which can occur from overuse or a sudden injury
• Fractured vertebrae
• Herniated disc, or damage to the cushioning pad between vertebrae
• Infection of the spinal cord, fluid, or discs
• Osteoarthritis, a degenerative bone disease
• Spondylolisthesis, a degenerative disc disease