Epidural Steroid Injection, Lateral View

Description

Lumbar vertebrae and the posterior elements dominate this lateral profile, with the spinous processes projecting posteriorly and the laminae forming the dorsal boundary of the vertebral canal. A spinal needle advances from a posterior approach through the supraspinous and interspinous ligaments toward the ligamentum flavum, then into the lumbar epidural space that lies external to the dura mater. Anterior to the epidural compartment, the posterior longitudinal ligament and vertebral bodies align in a gentle lumbar lordosis, while the dural sac continues caudally beyond the termination of the spinal cord into the region occupied by the cauda equina. Depth matters. Epidural steroid injection is a common intervention for lumbar radicular pain from disc herniation or foraminal stenosis, and the lateral perspective is the workhorse for teaching needle depth relative to the ligamentum flavum, epidural fat, and dural sac. By fixing the needle trajectory against the osseous landmarks, the illustration clarifies the clinical target zone where injectate should spread without intrathecal entry, a distinction that underlies the loss-of-resistance technique and explains complications such as inadvertent dural puncture with postdural puncture headache. The relationship of the needle tip to the posterior canal also supports discussion of epidural hematoma risk in anticoagulated patients and the need to avoid advancing when bony contact suggests laminar impingement. Pain medicine lectures, anesthesia rotation handouts, and spine clinic consent materials often need a single, unambiguous frame that anchors terminology like interlaminar approach, epidural space, and dural sac to realistic lumbar anatomy. Medical publishers can also pair this illustration with fluoroscopy or MRI figures to align procedural anatomy with imaging-based landmarks. Anatomical accuracy verified by SciePro's Medical Advisory Board.