Anatomy of Mid Back
- Thoracic Vertebrae
- Rib Articulation
- Thoracic Discs
- Thoracic Facet Joints
- Thoracic Spinal Nerves
- Thoracic Spinal Musculature
The thoracic spine contains 12 medium sized vertebrae all of which form articulations (joints) with 2 opposing ribs. Like the other spinal vertebrae, the thoracic vertebrae act as attachments for muscles and ligaments in the mid spine and also encase and protect the median aspect of the spinal cord and thoracic nerve roots.
Because the thoracic vertebrae form relatively strong articulations with the ribs, the mobility of the thoracic spine is less than that of the cervical and lumbar spines. However, this same characteristic also protects the thoracic spinal discs and facet joints from the wear and tear experienced by these structures in the other areas of the spine.
Common vertebral problems in the thoracic spine include vertebral subluxations, a condition where the vertebrae of the thoracic spine become statically misaligned and/or function abnormally resulting in pain, muscle spasm, and sometime nerve malfunction.
The thoracic is unique in that each of it's vertebrae attaches to a pair of ribs. There are 12 thoracic vertebrae and thus, 24 ribs (12 on the left and 12 on the right). Just like adjacent connecting vertebrae can misalign and biomechanically malfunction, so too can the thoracic vertebrae and it's adjacent ribs. When ribs "go out" or misalign in relation to their connecting vertebrae, the individual will often experience sharp pains in the area of the misaligned rib head, especially on twisting movements of the torso.
As with vertebral subluxations, chiropractors can successfully treat rib misalignments with the chiropractic spinal adjustment. The adjustment repositions the rib to it correct position and normalizes impaired motion patterns.
Thoracic Intervertebral Discs
The intervertebral discs in the thoracic spine are located between adjacent vertebrae. They function as spacers to provide clearance for exiting spinal nerves, as connectors to link adjacent vertebrae together and allow for movement, and also as spinal shock absorbers.
The discs of the thoracic spine are less likely to become injured compared to those of the cervical and lumbar spines, making up only 2% of intervertebral disc herniations. This is because of the rib articulations made by the vertebrae which significantly increases the stability of the thoracic spine. This does not mean that the discs of the thoracic are immune from damage, rather, statistically less likely to become injured.
Thoracic Facet Joints
The facet joints in the thoracic spine allow for considerable amounts of flexion and extension. The facet joints can become injured with excessive amounts of rotation and extension. Golfers are prime candidates for facet joint injury due to their repetitive twisting motions as they swing their golf clubs. When injured, pain is often sharp and localized to the area of the affected facet joint.
Thoracic Spinal Nerves
The thoracic spinal nerve roots exit openings formed between adjacent thoracic vertebrae termed the intervertebral foramina or IVF. The spinal nerves from the thoracic spine innervate the many muscles of the back as well as the many visceral organs and tissues of the chest and abdominal regions.
Spinal nerve root irritation or compression in the thoracic region commonly leads to intercostal pain (between the ribs). Sharp shooting pains are often experienced along the path of the ribs. Additionally, an increased susceptibility to herpes zoster or "shingles" in some individuals (generally the elderly or immunocompromised) is thought to occur when the thoracic spinal nerves are irritated or compressed. Herpes zoster involves infection to an area of the nerve root, the dorsal root ganglion, with the herpes virus.
Thoracic Spinal Musculature
The paraspinal muscles of the thoracic spine are numerous. They are responsible for the majority of trunkal movements as well as a number of upper extremity movements and are a common source of injury and pain.
Over exertion of the muscles from lifting and pulling and poor posture are the major contributors in mid back strains. Pain originating from these muscles characteristically produces a dull generalized ache.