by Erik Dalton PhD.
There are only a few places where the nervous system can be properly tuned, and these “adjusting knobs” are the bones that directly attach to the dura mater. Faulty alignment or fixations in any bone of the cranial vault or spine will over stretch, torsion, deform or drag on the dural membrane, disrupting its ability to send or receive reliable signals from musculoskeletal and visceral structures. These aberrant dural stresses frequently manifest as spasm and pain, and are often misinterpreted as muscle problems. Therapists greatly benefit from the ability to quickly distinguish between common myofascial pain syndromes and true adverse dural tension signs.
Poor alignment at C2 (axis) can contribute to head and neck pain due to the unusual dural membranous attachment to the anterior bodies of the C2-3 joints. In the embryo, the rod-shaped notochord develops at the axis. Since the notochord is central to the development of the axial skeleton and instrumental in determining the final construction of the central nervous system, any distortion here can set-off tonic neck reflexes that travel down intersegmental pathways creating postural havoc in the thorax and pelvis. Therefore, we must appreciate this area as the body’s premiere neurological and biomechanical center. (Gotta’ get it right here folks).
All is well so long as the axial skeleton is properly aligned and the spinal cord’s protective dural covering is not overstretched by cranial or sacral asymmetries or forward head postures. Regrettably, this tough dural tube is commonly distorted by traumatic events or during acts such as prolonged stomach sleeping or poor ergonomic sitting. When the joints of the upper cervical complex (O-A and A-A) and their supporting soft tissues become strained and motion restricted, compensations often travel down the kinetic chain and lock the C2-3 facet joint closed unilaterally. Constant jamming together of the C2-3 joint leads to cartilage derangement which alters the joints axis of rotation, distorts the dural membrane and reciprocally spasms the sensitive suboccipital muscles.
Muscles or ligaments?
Most of us refer to the ‘deep eight’ suboccipitals as muscles…and that’s OK. However, many researchers believe their primary function is that of proprioception i.e., helping the vestibular system interpret where the head is in space. Or, as Ida Rolf would say: “Suboccipitals tell the brain which end is up!” Since the suboccipitals contain Golgi end organs instead of Golgi tendon organs (as they attach to the skull), by definition, they should be classified as ligaments. So why do they contain end-organs instead of tendon organs? Mother Nature had a grand design here.
If the suboccipitals contained tendon organs, they would be affected by any tensional changes in their synergistic stabilizers, e.g., muscles that perform the same duty at a given joint (semispinalis capitis, splenius capitis, longissimus capitis, etc.). Since end-organs are not affected by these tensional changes, it allows the suboccipitals to more accurately monitor and report alterations in head-on-neck movements.
Suboccipital Triangle and Nerve Irritation
It has been estimated that greater than 80% of headaches are related to ‘stress’…both physical (poor posture, joint dysfunction, etc.) and psychological (marriage or work-related worries, etc.). Regardless of the type of dis-stress involved, the events leading to the onset of headache pain remain the same. Several of the nerves that exit the upper cervical complex travel back over the top of the head to the forehead. These nerves must pass through a triangle of muscles called the suboccipital triangle (Figure 1). When the suboccipitals become irritated from physical strain or emotional stressors, they tighten…squashing the nerves passing through the triangle.
The inferior oblique shown above originates at the C2 spinous process and runs laterally (and a little superiorly) to attach to the atlas transverse process. Visualize how a tight/short inferior oblique on the left could restrain the atlas (and head) from rotating right. When the person quickly looks over her right shoulder, the left inferior facet joint at C2 gets crammed closed on C3. This is a common area of dural membrane distortion as well as a key area of nerve impingement leading to headaches. Try the maneuver with a plastic spine.
When a rotated axis combines forces with an already overstretched dural tube from cranial or sacral distortions, a full-blown central nervous system assault suddenly transpires. To relieve the client’s agonizing symptoms and restore healthy functioning, manual therapists must first understand how the axis becomes misaligned and which techniques work best for releasing the disgruntled dural membrane. Figure 2 demonstrates a good sidelying technique to correct a tight fibrotic right inferior oblique muscle.
Therapist’s right thumb contacts C2 spinous with fingers draping right side of client’s face. As the thumb slides slightly laterally off C2, contact is made with the inferior oblique tendon. Client gently right rotates head against therapist’s resistance to a count of five and relaxes. Therapist maintains constant pressure until a release is palpated.
Long-standing pain often fades in memory as dural techniques are properly applied through training programs devoted to this intriguing area of manual therapy. Hands-on approaches for treating these conditions can best be learned by attending courses devoted exclusively to this very timely and rewarding body of work. By developing a comprehensive understanding of muscle/joint biomechanics involved in ‘dural drag’ and accompanying neck, head and low back pain, therapists can turn a therapeutic challenge into triumph.