Fig. 1.

Methodology. A. Lateral radiograph with planes positioned at the anterior quarter (X) and midpoint of the lateral neck of the superior articular process (Y). B. Direct lateral view of 3D model with planes positioned at the anterior quarter and midpoint. C. Posterior view of lumbar dorsal ramus. D. Inset of white box in C showing minimal distance (d) between the medial and lateral/intermediate branches of lumbar dorsal ramus. Dotted line indicates outline of superior articular process; MB, medial branch; LB/IB, lateral and intermediate branches; 1, mamillary process; 2, transverse process.