Written and illustrated by Tad Wanveer, L.M.B.T., C.S.T.-D.

“So let us consider the patient who has the disease and not the disease which has the patient and we will find repeatedly that it is the little things that are the big things in the science of osteopathy.” Beryl E. Arbuckle, D.O., F.A.C.O.P.

The Myodural Bridge: Small Size, Large Influence, MASSAGE MagazineThe myodural bridge (MDB) is a small ligament connecting a pair of deep, upper-neck muscles called rectus capitus posterior minor (RCPMi) to tissue covering the spinal cord, called the dura mater. There are three continuous and interconnected layers of fascia wrapped around the brain and spinal cord [the brain and spinal cord are referred to as the central nervous system (CNS)]. The layer of fascia hugging the brain and spinal cord is called the pia mater, the arachnoid membrane is a layer of fascia wrapping around the pia mater and the dura mater is a layer of fascia wrapping around the arachnoid membrane. All three layers plus cerebrospinal fluid are called the craniosacral system, which surrounds, protects, nourishes and cleanses the CNS. (Fig. 1)

The RCPMi muscles are part of a group of muscles, called suboccipital muscles, which are located at the base of the cranium. (Fig. 2)  The MDB attaches to the two RCPMi muscles and the dura mater. (Fig. 3) The MDB may become too lax or too tight for various reasons, and in response the dura mater can become irritated. Also, the MDB can twist, pull or shorten the dura mater, so abnormal tension would be transmitted throughout the craniosacral system.

How can MDB dysfunction cause symptoms?

The MDB is one of those “little things” that can lead to “big things,” such as chronic discomfort and pain and various forms of ill health. Some examples of how MDB dysfunction causes symptoms are listed below.

Chronic neck pain or headache may be caused when the MDB is too tight. This tightness can place excessive tension upon the dura mater, causing the activation of pain receptors within dura mater, which then refer pain signals to the neck or head.
 
The Myodural Bridge: Small Size, Large Influence, MASSAGE MagazineThe MDB helps maintain normal dura mater shape around the spinal cord, especially when the head moves into certain positions. If the MDB is too lax, the dura mater can abnormally fold down upon the spinal cord in the area of the MDB. This downward folding can cause cerebrospinal fluid congestion, as well as nerve root or spinal cord compression where the MDB attaches to the dura mater. As a result, nerve irritation can develop, which can lead to chronic pain. This pain is usually felt in the neck or head.

Dizziness and balance problems may arise if the RCPMi, or other suboccipital muscles, become weak or imbalanced to the degree they send muddled information to the brain about where the body is in space (called proprioceptive feedback). This can cause the brain to react in a chaotic fashion, leading to dizziness and balance problems, or a host of other issues, such as eye movement disorders, head tilt, difficulty reading or difficulty paying attention.
 
Movement disorders can occur when MDB strain transmits abnormal tension into the dura mater surrounding the cerebellum. Processes, such as monitoring, organizing and fine-tuning movement, take place in the cerebellum, so disruption in these processes can lead to such issues as difficulty controlling eye movement, inability to judge distance, moving awkwardly, slurred speech, weak muscles or movement tremors.

Coccygeal or pelvic floor pain can arise when the MDB is pulling the dura mater in such a way that the pull is transmitted to the sacrum or coccyx. This pull can cause fascial stress that alters the normal shape of nerves and blood vessels. As a consequence, blood vessels constrict or nerve control of blood vessels is altered, which can lead to an accumulation of waste and toxic elements. This buildup of elements can exhaust the tissue and irritate pain receptors, leading to coccyx or pelvic floor pain.

High blood pressure, headache, chronic fatigue, emotional stress and pain are some of the conditions that can be caused by autonomic nervous system (ANS) dysfunction. There seems to be a close connection between sensory cells in fascia that relay information to, and affect the function of, the ANS. Overly stressed fascia, as when the dura mater is strained by the MDB, can cause a disruption of the fight/flight/freeze portion of the ANS (called the smpathetic division). This can lead to chaotic ANS control of internal processes, such as heart rate, breathing, digestion, blood flow or body temperature. As a consequence, symptoms listed above, as well as others, including fainting spells, anxiety, irritable bowel syndrome, excessive sweating, blurred vision or numbness, can occur.

The Myodural Bridge: Small Size, Large Influence, MASSAGE MagazineHow can craniosacral therapy help?

Craniosacral therapy (CST) can help clients overcome dysfunction caused by MDB adverse strain by:

  • Mobilizing restrictive patterns of fascia throughout the body;
  • Normalizing the shape, function and balance of the suboccipital muscles, in particular the RCPMi;
  • Decreasing restrictions of the dura mater and craniosacral system;
  • Increasing the balanced movement of the dura mater and craniosacral system;
  • Calming irritation of the CNS and ANS;
  • De-stressing adverse strain of the cranial nerves and brainstem nuclei, especially the trigeminal nerve, which is a highly influential cranial nerve and is often affected by MDB dysfunction; or
  • Enhancing the movement of cerebrospinal fluid throughout the craniosacral system, which by its flow can aid correction of stressful neurological patterns.

Gentleness is a vital key to treatment

The area of the MDB is one of complexity, subtlety and sensitivity. Using the least amount of pressure needed, while sensing and following the response within the tissue, is an effective way to help the body correct abnormal strain in the MDB, dura mater, craniosacral system, RCPMi and other tissue or systems. Client response to CST seems most effective when the practitioner utilizes gentleness, rather than force, and maintains patience, rather than hurrying the tissue. CST works within the realm of micromovements.

Andrew Still, founder of osteopathy, said, “It may be that by measurement we can discover a variation one-hundredth of an inch from the normal, which, though infinitely small is nevertheless abnormal.” Delicacy and softness are keys to successful treatment of MDB dysfunction.

References
1. Arbuckle, Beryl E., DO, FACOP, The Selected Writings of Beryl E. Arbuckle, D.O., F.A.C.O.P., American Academy of Osteopathy, Indianapolis, Indiana, 1994.  
2. Biondi, David M., D.O., “Cervicogenic Headache: A Review of Diagnostic and Treatment Strategies,” Journal of the American Osteopathic Association, April 2005, Vol. 105. www.jaoa.org/cgi/content/full/105/4_suppl/16S
3. DiGiovanna, Eileen L., D.O., F.A.A.O., et al, An Osteopathic Approach to Diagnosis and Treatment, Lippincott Williams Wilkins, Philadelphia, Pennsylvania, 2005. 
4. Hallgren, Richard, Ph.D.,  “Magnetic Resonance Imaging of the Upper Cervical Spine, Detection of Atrophic Changes in Rectus Capitis Posterior Minor Muscles.” www.chiro.org/LINKS/FULL/Magnetic_Resonance_Imaging.html
5. Mays, Daniel T., Psy.D., “Treatment of Musculoskeletal Pain with Neuromuscular Calibration, A Retrospective Outcome Assessment,” http://www.nci-network.com/TreatmentOfMusculoskeletalPain.pdf
6. Schleip, Robert, “Fascial Plasticity–a new neurobiological explanation: Part 1,” Journal Of Bodywork And Movement Therapies, Jan. 2003, Elsevier Science Ltd.
7. Ibid, “Fascial Plasticity–a new neurobiological explanation: Part 2,” Journal Of Bodywork And Movement Therapies, April 2003, Elsevier Science Ltd.
8. Still, Andrew T., Philosophy and Mechanical Principles of Osteopathy, Hudson- Kimberly Publishing Co., Kansas, Missouri, 1902.
9. Upledger, John E., D.O., O.M.M., Cell Talk, Talking to Your Cell(f), North Atlantic Books, Berkeley, California, 2003.

Tad Wanveer, MASSAGE MagazineTad Wanveer, L.M.B.T., C.S.T.-D., is a licensed massage/bodywork therapist and is diplomat certified in craniosacral therapy (CST). After graduating from the Swedish Institute, College of Health Sciences in New York City in 1987, he established a private practice in New York City.  In 1993, he began specializing in CST.

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