Thoracic Spine: Anatomy Review and Clinical Implications

The thoracic spine is an anatomical region that is often skimmed over in physical therapy school (especially during clinical and practical exams). Students are taught basic anatomy and some assessment/treatment techniques, but often fail to integrate this information into actual clinical scenarios. While these fundamentals are important, several important anatomical considerations and clinical connections are often overlooked. The thoracic spine links two of the most commonly injured body parts: cervical and lumbar spine. With the continued development of our understanding of regional interdependence, it is becoming increasingly important to use a whole-body examination for each of our patients. This post is an in-depth review of the thoracic spine.

Anatomy:
When discussing thoracic spine anatomy, one of the first things to remember is that the thoracic spine is comprised of 12 vertebrae. These vertebrae have similar characteristics to the other vertebrae: a vertebral body (disk to vertebral body height ratio is 1:5), pedicles directed posterior from the body, lamina that connect to form a spinous process, and facets (Neumann, 2010). The transverse processes are directed posterolaterally and the spinous processes fall inferiorly (depending on the region). This orientation puts the transverse processes one segment below the corresponding spinous process. Clinically, this is an important consideration for palpation. T1-3 and T10-12 may actually have their spinous processes at the same level as the transverse processes (Egan et al, 2011).  The spinous processes of T4-T6 fall half a level below the transverse processes, while T7-9 spinous processes fall a full level below the transverse processes (this is the “rule of 3’s” which has limited support at the time, so should be applied with caution). The pedicles actually sit directly posterior from the vertebral body, making the vertebral canal narrower here compared to other parts of the spine. T4-9 is known as the critical zone because the vertebral canal is narrowest here; it also has reduced blood supply (Egan et al, 2011). For this reasons, T6 is a tension point. At T6, motion of the spinal cord versus canal converge in different directions, meaning restriction in neural/spinal mobility can occur and may need to be addressed. The superior and inferior facets in the thoracic region are oriented about 60 degrees from the horizontal plane and 20 degrees from the frontal plane with the inferior facets facing anteriorly, inferiorly, and slightly medially; the superior facets face posteriorly, superiorly, and slightly lateral. Something to consider is that there is no immediate change between cervical to thoracic vertebrae and thoracic to lumbar vertebrae. The superior thoracic vertebrae bare qualities more similar to the cervical spine and the inferior thoracic vertebrae more so resemble the lumbar spine.

Ribs:
Additionally,  when assessing the thoracic spine, one must consider the ribcage. There are 12 ribs (usually) in the body, just as there are 12 thoracic vertebrae. Ribs 1-7 are true ribs in that they attach directly to the sternum in the front of the body (Neumann, 2010). Ribs 8-12 are false ribs. Ribs 8-10 join in cartilage before attaching to the cartilage of the 7th rib. Ribs 11 and 12 are floating ribs and have no ventral attachments. Ribs 3-9 have demifacets on the thoracic vertebrae for attachment that span 2 vertebrae. Ribs 1, 11, and 12 have one facet on the corresponding vertebrae. The 2nd rib attaches to both T1 and T2 vertebrae. Additionally, ribs 1-10 have facet attachments at the costotransverse joints, while ribs 11-12 lack these as "floating ribs." Above T7, the rib portion of the costotransverse joints are concave, allowing for more rotation compared to the planar joints of the below T7 (Egan et al, 2011). The sympathetic chain lies on the anterior side of the rib heads next to the costovertebral joints.

Clinical Implications:
As stated previously, the fact that the thoracic spine connects the cervical spine to the lumbar spine is reason alone that this anatomical area should be considered for treatment. Think about the impact of posture. In most patients that sit for prolonged periods with a forward head posture, the anterior shift of the center of gravity places an excessive flexion moment arm to the thoracic spine, furthering the already kyphotic nature of the thoracic spine. As with any tissue, prolonged stress and creep eventually leads to pain when the tensile stiffness is no longer sufficient and the patient experiences pain. Training postural muscles is key to encouraging a more neutral posture that does not stress the tissues excessively. This may include spinal stabilizers and scapular stabilizers and should be dosed appropriately (likely want some high repetition-based exercises to improve endurance).

Consider facet restrictions: Limited joint mobility in one location often leads to hypermobility and pain in other regions, either nearby or distant. A joint dysfunction can often lead to hypertonic/painful muscle tissue near the joint as well. We can treat these restrictions with manual therapy and exercise. Two conditions less commonly discussed but seen relatively often include rib dysfunction and neural tension. Rib impairments are typically considered after a blow to the side or pain with breathing, but that is not always the case (making it harder to identify). A partially subluxed or restricted rib can be quite painful and present as thoracic paraspinal pain or even abdominal pain as the tip of a floating rib presses against the anterior tissue.

A potential location for pathology and treatment of neural tension is the thoracic spine. Remember that the thoracic spine contains the critical zone where the vertebral canal is narrowest. The spinal cord can easily become compressed here, leading to pain/neural tension along the path of a nerve. A nerve can become irritated anywhere in the body. Additionally, sometimes neural tension in the thoracic spine may be related to the cervical spine. With cervical radiculopathy or Cloward’s Area, thoracic/scapular pain can be coming from the cervical spine. When the patient presents with thoracic restrictions, a manipulation to the mid-thoracic spine often improves pain and neural tension by improving mobility. This doesn’t only apply to thoracic pain. There is research showing that patients with shoulder or neck pain may benefit from thoracic manipulation. In fact, there is a clinical prediction rule recommending thoracic manipulation for neck pain (non-validated):

• Symptoms < 30 days
  
• No symptoms distal to shoulder
  
• Looking up does not aggravate symptoms
  
• FABQ Physical Activity Score < 12
  
• Diminished upper thoracic spine kyphosis
  
• Cervical extension ROM < 30 deg      (Cleland et al, 2007)​

​In theory, why does this manipulation work? Think of it as a reset button as it also may have an impact on the sympathetic nervous system. In fact, if we are thinking about the nervous system as a whole, a manipulation to the thoracic spine can impact anywhere in the body, whether it be through improving neural mobility (all nerves are connected head to toe physically and electrically) or just as a novel stimulus to the nervous system! Whether you want to incorporate manual therapy, exercise or just implement part of your examination, consider assessing the thoracic spine for at least all spinal patients, if not more. While there are many methods of assessing the thoracic spine and rib cage, check out this video below detailing how we do some segmental mobility and gross motion assessment.

For more information on topics like these, check out our FREE Cervical Spine Mini Course on how to treat Cervical Radiculopathy!

References:
1. Cleland JA, Childs JD, Fritz JM, Whitman JM, Eberhart SL. "Development of a clinical prediction rule for guiding treatment of a subgroup of patients with neck    pain: use of thoracic spine manipulation, exercise, and patient education." Phys Ther. 2007 Jan.
2. ​Egan W, Burns S, Flynn T, and Ojha H. The Thoracic Spine and Rib Cage: Physical Therapy Patient Management Utilizing Current Evidence. Current Concepts of Orthopaedic Physical Therapy, 3rd Ed. La Crosse, WI. 2011.
3. Neumann, Donald. Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation. 2nd edition. St. Louis, MO: Mosby Elsevier, 2010. 322-323. Print