L4 or Fourth Lumbar Vertebra as, Posterior View

Description

Posteriorly, the L4 vertebra is defined by a broad spinous process projecting in the midline and thick paired laminae converging toward it to complete the posterior vertebral arch. Laterally, the pedicles frame the vertebral foramen and lead into the transverse processes, while the superior and inferior articular processes sit posterolaterally at the junctions of lamina and pedicle, forming the L3 to L4 and L4 to L5 zygapophysial (facet) joints. The pars interarticularis lies between the superior and inferior articular processes, just lateral to the lamina. Surface roughening along the spinous process and laminae marks attachment sites for multifidus and interspinous ligaments. A posterior L4 view matters because it clarifies the bony corridor used in posterior lumbar approaches, where the lamina, spinous process, and pars interarticularis guide level identification and safe decompression. Hypertrophy of the L4 to L5 facet joints and thickening along the laminae contribute to lumbar spinal stenosis, and the relationship between the lamina and pars is central when teaching spondylolysis, which most often occurs at L5 but is still assessed at adjacent levels. This angle also supports procedural anatomy for interlaminar access, where the interlaminar window at L4 to L5 is a common route to the epidural space. Spine anatomy courses, orthopedic and neurosurgical atlases, and radiology teaching files can pair this posterior bony view with oblique radiographs or CT to correlate the pars interarticularis and facet joint orientation at L4. It also fits patient education materials explaining lumbar laminectomy, medial facetectomy, or posterior element sources of low back pain. Anatomical accuracy verified by SciePro's Medical Advisory Board.