The thoracic spine has a significant influence on the way the neck works, even in not very active people, and has a massive impact on upper extremity function.
The thoracic spine does not have such a significant influence on lumbo-pelvic function, except in very active people or in people whose lumbar spine is only just coping.
The thoracic spine has a particular set of ways in which it is influenced by, and influences, the health and vitality of the person.
The critical mechanical focus of the thoracic spine is a) how well does it rotate and b) how well does it extend?
Failure to rotate and extend will affect a particular direction of neck rotation and (less so) side-bending. E.g. if some thoracic segments do not rotate well to the right, they will affect – mainly through myofascial effects – the way the neck moves to the right. This will affect the ability of the right shoulder joint to rise to 180 flexion.
Failure to rotate in a particular direction of one, or more, segments generally indicates stiffness of the opposite side – for example, if analysis shows that T3-5 does not rotate well to the right, then it is T3-5 on the left that is likely to be stiff and dysfunctional.
One-sided restrictions as in the example above are more common than ‘neutral’ bilateral stiffness at a particular level, particularly in young and middle-aged people.
Thoracic vertebral segment ‘stiffness’ will warp and distort natural rib movement as the thoracic cage flexes and rotates – in some patients this may result in anterior rib / sternal area discomfort.
Abnormal muscle tone and pain generally develops on the opposite side to the stiffness – in other words, they occur on the same side as the difficulty turning.
Stringy, thinner (less muscle mass) and less tender segment musculature generally develop on the same side as the stiffness.
The role of manipulation is to release this stiffness by restoring the failed rotation and extension at the segment in a particular direction – in other words, manipulation must be directional in its purpose.
Regarding the actual manipulative technique, this is achieved by manipulative approaches that aim to challenge the inability of the segment to rotate in the desired direction – minimal amplitude techniques can do this in ways that do not discomfort the patient.
Finally, manipulation is thus generally performed on the non-tender side of the thoracic spine – in the case of a patient who has thoracic pain, a higher level of thinking should be done if one is tempted to manipulate the same side and same level as the pain.