In several upper cervical theories it is hypothesized that an atlas vertebra misalingned out of a presumptive normal horizontal plane causes a change in the vertical orientation and center of gravity of the skull. Resultant altered weight bearing of the atlanto-occipital and atlanto-axial joints are suspected of stimulating joint mechanorceptors and aberrant proprioceptive spinal input, which initiate spinal reflexes causing body distortion and a functional or contracted leg-leg length inequality.
Two case studies in which there was unusual joint alignment in the upper cervical spine- atlantaxial rotatory fixation and a hypoplastic occipital condyle- are reviewed. This paper discusses how the clinical findings in these cases of joint alignment anomalies may alter hypotheses regarding the causation of mechanorecptor stimulation, leg length inequality, concepts of normal atlas orientation, a medical counterpart of a chiropractic subluxation, and the necessity of routinely post-x-raying patients in an attempt to establish physical equilibrium.
Author Keywords: Chiropractic, specific upper cervical, proprioceptive insult hypothesis
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