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Tone: The Importance of Sagittal Alignment

Over the years, there have been many meanings of the word “Tone”. It can be used to describe the sound of music, the hue of many colors, or the quality of a conversation. In D.D. Palmer’s 1910, “Text-Book of the Science, Art and Philosophy of Chiropractic”, it was given a new meaning:

“Life is the expression of tone. In that sentence is the basic principle of Chiropractic. Tone is the normal degree of nerve tension.” [1] 


Andrew Verdaguer

Andrew Verdaguer

In order to understand the importance of tone, let us take a look at the spinal cord. The average human spinal cord is between 43 and 45cm in length, stretching from the foramen magnum to the third Lumbar vertebra. The spinal cord, carrying all of our most valuable information from the brain to the rest of our bodies, is supported and held in place with dentate ligaments that stretch from the Arachnoid Mater to the periosteum of the vertebral canal. These dentate ligaments actually keep our spinal cord in a permanently shortened state; removing the dentate ligaments from the spinal cord results in a lengthening of the cord by about 10% due to its own weight [2]. This natural lengthening is an unraveling of folds within the spinal cord that exist to allow the body to flex and extend. This keeps the nerves well within their elastic range and prevents the cord from experiencing any injury from tension or stretching.


However, when nerves are stretched past their elastic zone, damage ensues. A study from UCSD [3] showed that nerve tension of only 6% could decrease nerve conduction by 70% after one hour and nerve tension of 12% could completely stop all nerve conduction after one hour. More serious problems such as ischemic necrosis of nerve tissue, which can result in permanent limb dysfunction such as drop foot, has been shown to occur at only 15% nerve tension. If the natural folds of our spinal cord were to disappear, our nerve conduction would be dramatically impaired. Over time, this change in nerve tension that we call tone could result in long term health issues.

When we have improper sagittal alignment of our spine, such as anterior head carriage with underlying cervical flexion, this is exactly what happens. A study by Kitahara et al. compared cervical cord lengths in neutral, extended, and flexed positions of the neck and found that “the cervical spinal canal elongated resulting in stretching and lengthening the cord,” due to increased increased longitudinal and transverse forces within the spinal canal [4]. Not only can improper alignment of the spine create degeneration of the bones and cartilage, but it can physically alter the superhighway of nerves that are supposed to be relaying messages to every cell, tissue, and organ of the body.

While a chiropractic adjustment is unlikely to make any permanent structural changes to the spine, there are still other ways that we can use tone in order to improve one’s sagittal alignment. For instance, changing muscle tone through proper exercise can correct and stabilize postural distortions that lead to spinal misalignments. Changing the tone of your voice during a difficult conversation can make it easier to keep your head held high and avoid the forward head posture that comes with slouching. Changing the tone of the music playing can get you off the couch and moving in the way your body was designed.

Some aspects of chiropractic may have become outdated since D.D. Palmer published his first manual over a century ago, but the idea that “Life is the expression of tone” still certainly holds true.


  1. Palmer, D., 1910. Text-Book Of The Science, Art, And Philosophy Of Chiropractic. Portland, OR: Portland Printing House Company, p.7.
  2. White, Augustus, and Manohar Panjabi. Clinical Biomechanics Of The Spine. 1st ed., J.B. Lippincott Company, 1978, pp. 51-55.
  3. Wall EJ, Massie JB, Kwan MK, Rydevik BL, Myers RR, Garfin SR. Experimental stretch neuropathy. Changes in nerve conduction under tension. J Bone Joint Surg Br. 1992;74(1):126‐129.
  4. KITAHARA, Yukio et al. “Effect Of Spinal Cord Stretching Due To Head Flexion On Intramedullary Pressure”. Neurologia Medico-Chirurgica, vol 35, no. 5, 1995, pp. 285-288. Japan Neurosurgical Society, doi:10.2176/nmc.35.285.

This article first appeared in the May 2020 issue of Lifelines, the Life West student magazine.


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