The regions of the back correspond with the different designations for the spinal vertebrae. The lumbar region is located just below the thoracic and right above the sacral vertebrae. To the naked eye, the lumbar region curves just above the buttocks and forms the small of the back. The fourth lumbar spine vertebra (L4) is located towards the bottom of the lumbar section, near the sacral vertebrae at the bottom of the spine. Like the other lumbar spinal bones, L4 primarily provides protection to the spinal cord. However, they are larger than the thoracic or cervical vertebrae, as they have to bear the weight of the spine and the head. Also, it features a number of processes and groves where muscles attach. This includes the spinous, transverse and the inferior and superior articular processes. The fourth lumbar spine vertebra (L4) does not feature an articulation into rib bones. Ribs are the territory of the thoracic vertebrae. Like the rest of the spinal vertebrae, L4 articulates with other spinal vertebrae through circular cartilage, called annulus discs.
Written and medically reviewed by the Healthline Editorial Team
In Depth: L4