Fifth Lumbar Vertebra L5, Lateral View

Description

Seen in lateral profile, the male fifth lumbar vertebra (L5) sits inferior to L4 and immediately superior to the sacral base (S1), with the broad vertebral body positioned anterior to the vertebral arch. Posteriorly, the pedicles and laminae frame the vertebral foramen, leading into a short, stout spinous process. The transverse processes project laterally with a characteristic caudal tilt, while the superior and inferior articular processes form the L4 to L5 and L5 to S1 zygapophysial joints. Intervertebral discs separate the vertebral bodies, with the lumbosacral disc at L5 to S1 appearing thick in this region. L5 matters because it is the keystone between the mobile lumbar spine and the fixed pelvis, and the lateral silhouette clarifies the lumbosacral angle and the wedge-like geometry that concentrates shear at L5 to S1. This is the level where isthmic spondylolisthesis often declares itself, after a pars interarticularis defect allows anterior translation of L5 on S1. Disc herniation at L4 to L5 can compress the traversing L5 nerve root, while pathology at L5 to S1 more often affects S1, a distinction that becomes intuitive when you can visualize the segmental relationships in profile. A frequent pain generator. Use this asset to anchor teaching on lumbar load transfer in gross anatomy, orthopaedics, and radiology modules, or to illustrate textbook and journal figures discussing degenerative disc disease, spondylolysis, and lumbosacral junction biomechanics. It also reads well in patient-facing spine education where the relationship of L5 to the sacrum needs to be unmistakable. Anatomical accuracy verified by SciePro's Medical Advisory Board.