The L1 vertebra is the first lumbar vertebra in the lower back, located just below the thoracic vertebrae. It plays a crucial role in supporting the upper body and allowing for movement and flexibility in the lower spine. The lumbar region consists of five vertebrae, labeled L1 to L5, and is essential for weight-bearing and mobility. The L1 vertebra is part of the spinal column, which protects the spinal cord and provides structural support. It connects to the intervertebral discs, which act as cushions between the vertebrae, and is involved in various movements, such as bending and twisting.