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Table 2 Orthopedic parameters, including landmarks and definitions

From: Therapeutic effects of functional orthodontic appliances on cervical spine posture: a retrospective cephalometric study

Atlas inclination (modified)

Angle from atlas plane to Frankfort horizontal plane.

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.