When thinking about the cervical spine, it is important to remember the human body is neurologically and anatomically asymmetrical with patterns that determine which side of the body we rely on more for a sense of stability and balance.1-2 Since we are all asymmetrical and driven by patterns that are neurologic and respiration driven, we can predict and test for which side of the body we rely on most.
As Ron Hruska, PT, MPA, founder of PRI says, "Thank goodness for asymmetries, for without them we would have a hard time overcoming bilateral compensatory based inertia and compensatory neuromuscular processes that are based on the 'need' or 'belief' that humans behavior is dependent on symmetry."
Two Necks: The Tug-of-War
This is true of the cervical spine. Typically, the muscles on the right side of the neck become more dominate or biased than the left side. An example of this on visual inspection is that a right SCM will often be more prominent than the left.3,5
Over time, a tug-of war within the neck can occur caused by compensatory patterns and will restrict rotational movement of the neck, while causing a flattening or reversal of the normal cervical lordosis. This will be evidenced by the left SCM becoming as prominent as the right. One of the many reasons is, but not limited to, an inability to manage airflow with an overreliance on neck accessory muscles of respiration.
This begins to describe the statement that we have "two necks," as we dive deeper into polyarticular chains of muscles. The group of muscles described by the Postural Restoration Institute is called the Temporal Mandibular Cervical Chain (TMCC) and exists on both sides of the neck. Their role is to move, support and position a neck and cranium.
This group of muscles includes the temporalis anterior, masseter, medial pterygoid, rectus capitis posterior major, obliquus capitis, rectus capitis anterior, longus capitis and longus colli.5 Note that there are three anatomical regions that comprise the right TMCC including the cranium (temporal), mandibular (jaw) and cervical (neck). The TMCC also includes three muscles that attach to the jaw and cranium exclusively, but have a strong influence from the neck.3,5
Like the right SCM, the right TMCC becomes dominate in individuals due to several factors including which leg is stance-phase dominate; how they breathe, sit and walk, trauma; sports injuries; ankle problems; or just our natural-born asymmetries driving a person to one side of the body.
However, it is the neck, specifically at the A/O articulation which also can be called O/A joint or articulation, that is driving not only the position of the cervical spine, but ultimately the cranium and jaw. The relationship of the cervical spine to the cranium and jaw becomes interwoven with a bridge that spans to osteopathic strain patterns of the skull, as well as dental occlusion, as it affects bite awareness and a feedback system that can determine and direct posture and scoliosis.4,6,8
The Concepts of Lateralization, Alternating and Reciprocating
For now, however, let's just stay with the neck and begin to discuss a PRI concept around lateralization. Most human beings love the right side of their body to a fault. Not that there is anything wrong with that; it's just that we get stuck on that side and don't know how to get to the left side consciously even though we think we can. However, there are PRI tests that can objectively determine positional bias.
There is a connection with the sacrum to the cranium via a "core link," as well as the cranium to the sacrum, which chiropractors and osteopaths have been looking at for decades.6 A PRI concept is that if person relies on right stance, they will also rely on their right TMCC as a continuum of a right-dominate neurologic pattern and position correlating with a stronger neurologic reference of the right atlas and occipital bone. PRI describes this as "lateralization." This means we love one side of our bodies and often rely on an end-range to a fault for a sense of neurologic stabilization.
It is not a problem that we are on one side of our body for a time. But we need to get off of it and get onto the other side in a process called alternating. Then we need to go back and forth through a "neutral" rest position (numerous PRI tests can determine this), which is called reciprocating.
What makes the cervical spine so critical, especially the O/A joint, is that the brainstem is directly affected at this region. The following is a quote from the a PRI course manual that has profound significance to our profession.
"The medulla oblongata extends well into the lower foramen magnum and the ligamentous ring that connects with the atlas, thus any occipital or atlanto-restricted torsion may produce abnormal pressure on this portion of the brain stem."5
One significant issue is that the lower olivary neurons in the brain stem are located in a position that can have too much compression on one side of the foramen magnum. These neurons help us "oscillate" or lateralize to the left and right and back again. If there is brainstem pressure at the O/A joint, an inability to shift our bodies laterally in a balanced fashion will occur.
Author's Note: Future articles in this series will explore the O/A joint, right TMCC, alignment of vertebrae, and how to define and achieve neutrality of the cervical spine. Objective PRI testing and treatment of the cervical spine will be presented.
References
When sports chiropractors first appeared at the Olympic Games in the 1980s, it was alongside individual athletes who had experienced the benefits of chiropractic care in their training and recovery processes at home. Fast forward to Paris 2024, where chiropractic care was available in the polyclinic for all athletes, and the attitude has now evolved to recognize that “every athlete deserves access to sports chiropractic."
It is estimated that 61% of patients with CTS avoid taking surgical options due to postoperative complications and costly surgical procedures. Chiropractic care offers a comprehensive and effective treatment for carpal tunnel syndrome, addressing the condition from multiple angles. Recent studies also have unveiled a game-changing adjunct to chiropractic treatments for CTS: nerve flossing.
Some doctors thrive in a personality-based clinic and have a loyal following no matter what services or equipment they offer, but for most chiropractic offices who are trying to grow and expand, new equipment purchases help us stay relevant and continue to service our client base in the best, most up-to-date manner possible. So, regarding equipment purchasing: should you lease, get a bank loan, or pay cash?
