Lumbar Spine Anatomy

The lumbar vertebrae exhibit distinct features, including massive reniform bodies, that differ from cervical and thoracic vertebrae. The anterior height of these vertebrae increases from L1 to L5, contributing to the lumbar spine’s lordotic curve. The pedicles, laminae, and transverse processes exhibit specific structural characteristics. Age-related changes, such as reduced bone density and height variations, impact the vertebrae. The lumbar spine is supported and stabilized by the joints and the various ligaments connecting the adjacent vertebrae, thus aiding in movement and load distribution. Intervertebral discs, comprising an outer annulus fibrosus (AF) and a central nucleus pulposus (NP), form secondary cartilaginous joints. The AF is rich in type I collagen for tensile strength, while the NP contains type II collagen and proteoglycans for hydration and compressibility. The lumbar vertebrae receive nutrition from lumbar arteries, which arise from the abdominal aorta, and venous blood drains through valveless vertebral venous plexuses, enabling potential sepsis and malignancy spread. The lumbar vertebral canal houses the spinal meninges, the terminal part of the spinal cord, nerve roots, radiculomedullary vessels, and the internal vertebral venous plexus. Termination of the spinal cord takes place at the inferior border of the first lumbar vertebra, and the spinal nerves that innervate the various back structures emerge obliquely from the intervertebral foramina.