I found an interesting article written by Dr. Craig Liebenson, one of foremost Chiropractic authorities on rehabilitation of the spine. This article touched on poor posture as it relates to the Thoracic and Cervical spine and how it can generate from the Thoracic spine due to excessive sitting and slouch.
The first part of the article discusses the biomechanics of the Thoracic spine and sitting. It gets a little wordy, but the point can be understood by anyone who sits a lot or has poor posture.
Biomechanical Underpinnings and Kinesiopathology
“The thoracic spine represents a critical, yet underappreciated spinal region.10 Of all structures, the thoracic spine is one of the most vulnerable in modern lifestyles. In the fetal posture, the entire spine is kyphotic. We are hardwired to achieve a stable, upright posture by four years of age, three yet due to television, soft couches, chairs, desks, computers, etc., the thoracic spine slips back into greater kyphosis. The result: straightening of the lower cervical lordosis with compensatory C0-C1 hyperextension, as the eyes must peer horizontally. In the lumbar spine, we find poor control of the natural lordosis with resultant disc vulnerability during activities of daily living, such as sitting, bending, twist, lifting, etc.
Having a stiff upper-thoracic spine also decreases our ability to activate the deep neck flexors and even the abdominals. With freely moveable vertebrae in this junctional area, we can achieve a balance between the extensors and deep neck flexors, which ironically, originate in the mid- to the upper thoracic region.3“
“We know that with cervical rotation, we should appreciate motion all the way down to T4. Typically, patients with this restriction do not lose much active range of motion. It has been demonstrated that a significant association exists between decreased mobility of the thoracic spine and the presence of patient-reported complaints associated with neck pain.78-9 In a controlled study, this treatment was determined effective by itself. 4“ Cleland showed that in select patients, thoracic spine manipulation provided a successful treatment for patients with neck pain. Thoracic spine mobilization or manipulation acted as a component of a multi-modal intervention demonstrated to be effective for the treatment of patients with shoulder impingement syndromes.