Epidural Steroid Injection Procedure In The Lumbar Spine, Posterior View

Description

Lumbar vertebrae form the central scaffold in this posterior view, with the spinous processes aligned in the midline and the laminae and facet (zygapophyseal) joints flanking them laterally. A spinal needle approaches from the posterolateral back, passing toward the ipsilateral interlaminar region and into the epidural space, which lies deep to the ligamentum flavum and posterior to the dural sac. The needle trajectory is lateral rather than midline, placing its tip near the lateral recess and proximal neural foramen where the exiting nerve root and dorsal root ganglion sit anterolaterally relative to the spinal canal. Epidural fat and the epidural venous plexus occupy this compartment. Lumbar epidural steroid injection is a standard nonoperative intervention for radicular pain from posterolateral disc herniation, foraminal stenosis, or inflammatory nerve root irritation, most often at L4 to L5 or L5 to S1. The posterolateral approach highlighted here aligns with clinical practice when targeting unilateral symptoms, where medication delivery near the affected nerve root can reduce chemical radiculitis while avoiding an overly medial needle path. Depth cues and separation of posterior elements from the epidural compartment make the ligamentum flavum, dural boundary, and lateral canal relationships easy to teach. Small distances matter. Use this illustration in pain medicine and anesthesiology teaching files, spine surgery and physiatry lectures on interventional management of lumbar radiculopathy, and publisher-ready figures explaining epidural space anatomy and needle approach for informed consent materials. Anatomical accuracy verified by SciePro's Medical Advisory Board.