Chiropractic and Spinal Alignment and Cervical Curve

by Frank M. Painter, D.C.

Structure and Function

Our spine is a “structural” unit.   There are 4 curves to the spine. Loss of structural integrity and/or normal function of the spine is the basis for the evolution of the vertebral subluxation. Abnormal stresses occur in the facets, discs and supporting tissues when normal motion of the spine is impaired. Chiropractic analysis should be aimed at locating the specific segments which are subluxated, as well as providing the means to “free” those segments.

The normal cervical lordosis (which extends from C1 to T2) should have a 17–24 cm. radius , based on the patient’s height. This is easily measured with the AcuArc ruler. Kim Christensen D.C. in his book “Clinical Chiropractic Biomechanics” states, “Spinal biomechanical stability requires an optimal lordotic structure. The lordotic cervical & lumbar spine are the basis of the spine’s ability to resist axial stressors.”   A resistance factor in mechanical structure is expressed by the formula:

R = C2 + 1

where   R = resistance to axial pressure and   C = the number of curvatures.   Thus, the spine’s ability to resist axial stress, taking into account the cervical, thoracic and lumbar curves is:

R = 32+ 1 = 10

If we lose the cervical or lumbar curves, the formula is reduced to:

R = 22 + 1 = 5

Thus, a reduced cervical curve may result in a 50% reduction in the overall resistance of the spine to axial stress.

To define the cervical curve of the spine with a compass:

1.     Dot the posterior inferior aspect of C1’s anterior arch. (see Figure 2)

2.     Dot the anterior superior aspect of the vertebral body of T2. (see Figure 2)

3.     Set your compass for the distance between these 2 points. This length becomes the “chord” length of that patient’s curve.   Now, swing arcs back from the C1 and T2 points, with the compass set using the chord length, to locate the point which will describe the optimum spinal curve. (See Figure 1 + 2)   Then set the compass on that radius center-point, and use that same chord length to strike the radius of the cervical curve at the anterior vertebral bodies. (See Figure 2)   Note that ALL the vertebra should be on this curved line, with a radius between 17–24 cm., depending on patient height.

Figure 1

Figure 2
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The picture on the left is an example of perfect cervical lordosis. All segments should be on Georges’s line (one curved line).   There should be an even spacing between each spinous process. Positioning of the head and spine should also be assessed for anterior head placement (also known as Forward Head Posture).   The normal cervical lordosis (which extends from C1 to T2) should have a 17–24 cm. radius, based on the patient’s height. This is easily measured with the AcuArc ruler. The posterior arch of Atlas should be centered in the space between occiput and the C2 spinous process. If C1’s posterior arch “crowds” occiput, it is labelled as an “inferior” Atlas. If it crowds C2, it is labelled “superior”. The normal Atlas Plane line would be 18–24 degrees superior to the bottom of the film. A line under the bottom of the C2 body (Whitehorn’s line) should be parallel with the floor.


Source:  Chiro .org