Suggestion
Paradoxically, knowledge of nerve-paths may lead to error. By the law of expectancy, we are prone to find what we look for and if we hold too strongly to the belief that because we have found one or two points of tenderness we must find a series of points extending along a mentally pictured nerve-path, we may search until we falsely believe that we have found this series.
Likewise the patient, having been carefully informed as to the manner of procedure and knowing what we expect to discover, may unconsciously deceive us by feeling tenderness in response to suggestion, where no real impingement exists.