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Posterior Rami of Lumbar Nerves

rami posteriores nervorum lumbalium

The lumbar dorsal rami arise from each lumbar spinal nerve after it exits the intervertebral foramen and divide into medial and lateral branches. The medial branches cross the transverse process-articular process junction at each level, supplying the facet joint at that level and the one below (each facet joint is supplied by medial branches from two consecutive levels). The lateral branches supply the iliocostalis and longissimus muscles and the skin of the posterior lumbar and gluteal regions (as the superior cluneal nerves at L1-L3).

Region: Lower Back

Clinical Relevance

Clinical Notes

The lumbar medial branch nerves are the primary targets for lumbar facet joint denervation in chronic low back pain. Fluoroscopy-guided lumbar medial branch blocks at the transverse process-superior articular process junction at L3-L4-L5 and the sacral ala (for the L5 dorsal ramus) provide diagnostic confirmation of facet-mediated pain, and radiofrequency ablation (RFA) of these branches provides 6-24 months of relief. The standard diagnostic requirement is two positive medial branch blocks before proceeding to RFA, which ablates the nerves at their bony groove positions.

Pathology

Common Injuries & Conditions

Lumbar Medial Branch Radiofrequency Ablation for Facet Pain

Lumbar facet joint pain confirmed by dual medial branch blocks is treated by radiofrequency ablation of the medial branch nerves at the transverse process-facet junction, producing thermal neurotomy that provides 6-18 months of pain relief; repeat RFA is performed when pain returns as the nerve regenerates.