The lower back comprises the lumbar spine, which is formed by vertebral bones, intervertebral discs, nerves, muscles, ligaments, and blood vessels. The spinal cord ends at the top of the lumbar spine, and the remaining nerve roots, called the cauda equina, descend down the remainder of the spinal canal.
While the lumbar spine is sturdy and resilient, it is subject to a high degree of stress and loads, which may cause various problems, resulting in pain. This article provides an overview of the lumbar spine including its anatomy and the potential problems that can occur in this region.
Functions of the Lumbar Spine
The lower back performs the following important functions:
- Support and stabilize the upper body. The 5 lumbar vertebrae are the largest compared to other spinal regions.1,2 In conjunction with the muscles and ligaments, these vertebrae help support the weight of the upper body, including the head and neck. The lumbar spine also transfers loads from the upper body to the legs.2
- Allow truncal movements. The lower back is the primary facilitator for movements of the trunk in various directions, including front and back, side to side, and twisting movements.3 Movement mostly occurs in the last two vertebral levels.4
- Protect the spinal cord and cauda equina. The upper lumbar vertebrae protect the spinal cord in their vertebral arches. The lower vertebrae provide a bony enclosure for the cauda equina nerves that descend from the spinal cord.
- Control leg movements. The lumbar spinal nerves that branch off from the spinal cord and cauda equina to control movements and sensation in the legs.
When viewed from the side, the lumbar spine has a concave lordotic curve that helps distribute weights and reduce the concentration of stresses. An increase or decrease in this lordosis may contribute to lower back pain.2