D.D. Palmer, wrote extensively about the concept of tone. According to Palmer: "Life is the expression of tone. In that sentence is the basic principle of Chiropractic. Tone is the normal degree of nerve tension. Tone is expressed in functions by the normal elasticity, activity, strength and excitability of the various organs, as observed in a state of health. Consequently, the cause of disease is any variation of tone – nerves too tense or too slack."1
Palmer's tonal model is inherent in the modern concept of "tensegrity." Tensegrity is maintained in "a system that stabilizes itself mechanically because of the way tensional and compressive forces are distributed and balanced within the structure."2 In living cells, tensegrity is maintained by contractile microfilaments, which form a lattice that reorganizes locally into different forms.
The biological implications of tensegrity are described by a medical physician, Ingber: "Remarkably, tensegrity may even explain how all (these) phenomena are so perfectly coordinated in a living creature. At the Johns Hopkins School of Medicine, Donald S. Coffey and Kenneth J. Pienta found that tensegrity structures function as coupled harmonic oscillators. DNA, nuclei, cytoskeletal filaments, membrane ion channels and entire living cells and tissues exhibit characteristic resonant frequencies of vibration. Very simply, transmission of tension through a tensegrity array means to distribute forces to all interconnected elements and, at the same time, to couple, or 'tune,' the whole system mechanically as one."2 Tensegrity is not limited to the cellular level, but is operative on all anatomical levels.
Ingber also wrote, "Cells sense mechanical forces and convert them into changes in intracellular biochemistry and gene expression – a process called 'mechanotransduction.' This work has revealed that molecules, cells, tissues, organs, and our entire bodies use 'tensegrity' architecture to mechanically stabilize their shape, and to seamlessly integrate structure and function at all size scales."3
Tone and tensegrity are elegant theoretical models with practical clinical implications. D.D. Palmer wrote: "Tone, in biology, is the normal tension or firmness of nerves, muscles or organs, the renitent, elastic force acting against an impulse. Any deviation from normal tone, that of being too tense or too slack, causes a condition of renitence, too much elastic force, too great resistance, a condition expressed in function as disease."4
Functional consequences of changes in tone have been described. John H. Craven, professor of philosophy at the Palmer School of Chiropractic, wrote: "We have seen that the normal air pressure at sea level is fifteen pounds to the square inch. In order that the body will not be crushed by this weight it is necessary to have an internal resistance to equal this weight. This internal resistance is maintained in the body by the tone of all of its parts; it is maintained by the expression of mental impulses in the tissue cells."5
In 1927, chiropractor Stephenson noted that cord tension and cord pressure may cause impingement upon the spinal cord.6 Nearly four decades later, neurosurgeon Breig described how adverse mechanical tension on the spinal cord may result in abnormal neurological function and the development of pathology.7-9 Pfluger, in his thesis, "The Meaning of Tensegrity Principles for Osteopathic Medicine," explained the role of tensegrity in cytology, differentiation, morphogenesis, and self-organizing systems.10
Wall, et al., reported the results of experimental stretch neuropathy in an animal model. At only 6 percent strain, the amplitude of the action potential had decreased by 70 percent at one hour and returned to normal during the recovery period. However, at 12 percent strain, conduction was completely blocked by one hour and showed minimal recovery.11
Health is dependent upon maintaining proper tone in the nervous system. As D.D. Palmer explained: "Life is action governed by intelligence. Intelligent life, the soul, depends upon the execution of functions. Functions performed by normal energy is health. Disease is the result of the performance of functions above or below a normal degree of activity. Impulses properly transmitted through nerves, result in functions being normally performed, a condition which results in health."12
Lee described the theoretical role of the central nervous system (CNS) in all disease processes in the journal Medical Hypotheses: "Every malfunction in the periphery (in contrast to the CNS) must be sensed by the CNS in order that corrective measures be taken ... the CNS is universally involved in all diseases, regardless of whether they originally arise from the periphery or are indigenous to the central nervous system; whether initiated by various infective agents, be it viral, bacterial, rickettsial or parasitical in nature or resulted from exposures to toxins, radiation, physical injuries, or emotional upheavals."13
The ability to maintain tone requires a nervous system free of interference. Restoration of tone is dependent upon correction of vertebral subluxations. Alterations in the tone of the somatic system may be evaluated using surface EMG. Altered autonomic tone may be evaluated using skin temperature and heart rate variability measurements. Such objective assessments14-17 have the potential to make chiropractic the dominant strategy of 21st century health care, as modern research vindicates the discoverer's vision.
- Palmer DD. Text-Book of the Science, Art and Philosophy of Chiropractic for Students and Practitioners. Portland Printing House Company. Portland, OR, 1910:7.
- Ingber DE. "The Architecture of Life." Scientific American, January 1998;278(1):48-57.
- Ingber DE. Tensegrity and mechanotransduction. J Bodyw Mov Ther, July 2008;12(3):198-200.
- Palmer DD, Op cit, page 659.
- Craven JH. A Text-Book on Hygiene and Pediatrics From A Chiropractic Standpoint. Hammond Press; WB Conkey Company: Chicago, IL, 1924:54.
- Stephenson RW. Chiropractic Textbook. Palmer School of Chiropractic: Davenport, IA. 1927:306.
- Breig A. The biomechanics of the spinal cord and its membranes in the spinal canal. Verh Anat Ges (German), 1965;115:49-69.
- Breig A, Turnbull I, Hassler O. Effects of mechanical stresses on the spinal in cervical spondylosis. A study on fresh cadaver material. J Neurosurg, July 1966;25(1):45-56.
- Breig A. Overstretching of and circumscribed pathological tension in the spinal cord - a basic cause of symptoms in cord disorders. J Biomech, January 1970;3(1):7-9.
- Pfluger C. "The Meaning of Tensegrity Principles for Osteopathic Medicine." M.S. thesis. Donau University Krems and the Vienna School of Osteopathy. October 2008.
- Wall EJ, Massie JB, Kwan MK, et al. Experimental stretch neuropathy. Changes in nerve conduction tension. J Bone Joint Surg (Br), 1992;74(1):126-129.
- Palmer DD, Op cit, page 661.
- Lee TN. Thalamic neuron theory: theoretical basis for the role played by the central nervous system (CNS) in the causes and cures of all diseases. Medical Hypotheses, 1994;43:285-302.
- McCoy M, Campbell I, Stone P, et al. Intra-examiner and inter-examiner reproducibility of paraspinal thermography. PLoS One, Feb. 11, 2011;6(2):e16535.
- Stein PK, Bosner MS, Kleiger RE, Conger BM. Heart rate variability: a measure of cardiac autonomic tone. American Heart Journal, May 1994;127(5):1376–1381.
- Kelly S, Boone WR. The clinical application of surface electromyography as an objective measure of change in the chiropractic assessment of patient progress: a pilot study. J Vertebral Subluxation Res, 1998;2(4).
- Kent C. Surface electromyography in the assessment of changes in paraspinal muscle activity associated with vertebral subluxation: a review. J Vertebral Subluxation Res, 1997;1(3).
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