The normal posterior atlantoaxial relationship

The relationship of the posterior aspects of the atlas and the axis were studied in 100 normal adult volunteers. The ratio of the height of the atlantal spinolaminar line to the atlantoaxial interspinous distance was found to be remarkably constant and was less than 2.0 in all men and women. This ratio should prove helpful in detecting hyperflexion injuries isolated to the atlantoaxial level.