Fig 1.

Photograph (A) and schematic drawing (B) of a right posterolateral view of a dissection of a posterior lumbar ramus and its divisions at L2–L3. The medial branch of a L2 posterior ramus (arrowheads) runs against the lateral surface of the caudal edge of the superior articular process (black curved arrow) and then passes under a ligament (long black arrow) connecting the accessory process (a) and the mamillary process (m). Note the lateral branch of L2 posterior ramus (long white arrow) and vessels (white curved arrow) as well as the duplicity of the medial branch in the fibroosseous canal (twin medial branch).