Fourth Lumbar Vertebra L4, Posterior View

Description

Centered on L4 in posterior view, the vertebral arch forms a broad ring around the vertebral foramen, with stout pedicles transitioning into thick laminae that meet at the midline spinous process. Lateral to the laminae, the transverse processes project laterally for muscle attachment, while the superior and inferior articular processes sit posterolaterally and bound the zygapophysial (facet) joints with L3 and L5. Inferiorly, the L4 posterior elements align toward the lumbosacral junction, where the sacrum becomes visible as the column transitions into the pelvis. Solid bone. Clear landmarks. Posterior L4 anatomy matters because this segment is a common reference point for both clinical localization and load transfer in the lumbar spine. The intercristal (Tuffier’s) line often crosses the L4 spinous process or the L4 to L5 interspace, guiding lumbar puncture and neuraxial anesthesia, so the relationship between the spinous process, laminae, and midline is more than academic. Facet orientation at L4 to L5 also helps explain mechanical low back pain patterns and the typical level of degenerative spondylolisthesis, where pars interarticularis stress and facet arthropathy change posterior element geometry and can contribute to canal or lateral recess stenosis. Use this illustration for gross anatomy and neuroanatomy teaching when introducing posterior vertebral elements, interlaminar spaces, and the clinical surface anatomy used for spinal procedures; it also fits well in orthopaedic and pain medicine materials covering L4 to L5 facet-mediated pain, laminectomy landmarks, or posterior approaches for decompression and fusion. Anatomical accuracy verified by SciePro's Medical Advisory Board.