The proprioceptive mechanistic model of somatic dysfunction proposed by Korr is accepted as the neurophysiologic basis of counterstrain by the developer of that manipulative technique. We suggest that the physician should also take into account the physical damage, if any, that the original trauma produced. We propose that with tissue injury, nociceptive reflexes could produce patterns of motion restriction opposite that predicted by a solely proprioceptive model. A nociceptive component is suggested as an explanation for the origin and maintenance of somatic dysfunction and its response to the counterstrain technique. In actuality, both proprioceptive and nociceptive responses may occur in dysfunctional states. Other physiologic responses also may be involved. These views are consistent with clinical experience.