Atlas inclination (modified) | Angle from atlas plane to Frankfort horizontal plane. |
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Atlas plane (AT) | Line drawn through the most anterior and most posterior sites of the atlas. |
Chamberlain’s distance | Distance from dens tip to Chamberlain’s line. |
Chamberlain’s line (palato-occipital line) | Line drawn from posterior edge of hard palate to posterior edge of foramen magnum. |
Clivus-dens angle | Angle between dorsal ends of clivus and dens axis. |
Dorsal clivus boundary | Dorsal end of clivus |
Dorsal dens boundary | Dorsal end of dens axis |
McGregor’s line (palato-suboccipital line) | Line from posterior edge of hard palate to most inferior point of squama occipitalis. |
McRae’s line (foramen magnum line) | Line between anterior and posterior edges of foramen magnum. |
OPT line | Line drawn against the anterior cranial base to define the craniocervical angle. |
Powers ratio | Ratio between distances (i) opisthion to dens tip and (ii) Ba to projection center of arcus posterior atlantis. |
Ranawat’s line | Distance between a line connecting the projection centers of the anterior/posterior arches of the atlas and the center of the shadow of the axis vertebra. |
Redlund-Johnell/Petersson line | Distance between McGregor’s line and center of inferior endplate of second cervical vertebra (mC2) |
Solow/Tallgren sum (modified) | Sum of angles formed by linear parameters OPT, CVT (line through spC2 und pC2), NL, NSL and ML to the Frankfort horizontal plane. |