and continuous as it merges with the connective tissue sheaths that surround the nerves, muscles, and organs of the body. 3, 6, 7, 8
Research has shown that the dura is richly innervated and contains free nerve endings that act as nociceptors and mechanoreceptors, enabling it to detect mechanical deformation, including stretching, pressure, or tension within the meningeal layers. 9, 10 It has been proposed that these signals can
2, 11, 12 contribute to protective reflexes which prompt muscle contractions in nearby structures to protect the CNS.
Due to its anatomical attachments and its neural sensitivity, the dura mater acts as a neuromeningeal interface which monitors the position and movement of the various bony structures to which it is attached. It continually communicates this information to the CNS, which responds and adapts accordingly. 2, 6, 12 It can be inferred that when a Bowen move or procedure affects the position or movement of any osseous site to which the dura mater is attached it may induce a functional response within the CNS. 13
The Central Nervous System Sets the Tone More than a hundred years ago, D. D. Palmer, the founder of chiropractic famously stated,‘ Life is the expression of tone. In that sentence is the basic principle of chiropractic’. 14 In his 1927 Chiropractic Textbook, Ralph W. Stephenson explored the idea that tension within the dura mater and spinal cord could lead to neurological dysfunction, potentially resulting in various neurological and musculoskeletal symptoms, as well as other health issues. 15 The concept was further developed when the term‘ Adverse Mechanical Tension’ was formally introduced by neurosurgeon Alf Breig in his 1978 publication Adverse Mechanical Tension in the Central Nervous System. In his pioneering work on the biomechanics of the CNS, Breig explored how tension could affect the spinal cord and nerve roots, potentially leading to distant neurological symptoms, and he maintained that the nervous system must be treated as a continuous tract of nervous and supporting tissues. 16
Fascial and Neural Continuity Palmer, Stephenson, and Breig all recognised the extensive fascial and neural continuity provided by the dura mater and they all recognised that restrictions or stress affecting the dura can lead to altered muscle tone elsewhere in the body. These observations form important foundations for numerous schools of chiropractic, 17, 18 osteopathy, 19, 20 and Bowen therapy, 21 wherein manual therapists assess muscle tone not just locally, but as a reflection of central dural tension.
Biomechanical dysfunction or restriction affecting the sites of dural attachment can generate tensions that spread through the whole dural system. 8, 17, 18, 22 In the context of chiropractic neurology or craniosacral therapy, such a dysfunction would be viewed as a global lesion and could have the potential to affect neurological flow, cerebrospinal fluid dynamics, and
20, 22- the entire body’ s postural tone.
25
The basic premise here is a simple one: structural integrity of the musculoskeletal system contributes to optimum function of the CNS. When this is happening, there is likely to be symmetry of tone on either side of the body. When biomechanical disturbance affects any of the sites of dural attachment it can result in the development of asymmetrical tensions on either side of the spine. 23-25 Clinically, these tension states can be observed and traced back to their site of origin. 23-26 In this context, tonal asymmetry becomes a valuable guide to locating and correcting spinal and
21-25, 27, 28 cranial dysfunction.