Roentgenographic documentation of atlanto-occipital sidebending.

It is assumed that the atlas (C1) glides superiorly and laterally along the occipital (C0) condyle during translatory motion of the head in the opposite direction. To provide roentgenographic documentation, a translatory test of atlanto-occipital (C0-C1) motion was performed to the left and to the right on a healthy, asymptomatic volunteer subject. Roentgenographic examination was made at the extreme in each direction. The films indicate the change in atlantal position relative to the occiput and support the assumption. A translation of the head in the coronal plane to test for atlanto-occipital joint mobility is described.