The L3 vertebra is the third lumbar vertebra in the lower back, part of the lumbar spine, which consists of five vertebrae labeled L1 to L5. It plays a crucial role in supporting the upper body and allowing for movement and flexibility. The lumbar region is known for its strength, as it bears much of the body's weight and absorbs shock during activities like walking and lifting. Located between the L2 vertebra and L4 vertebra, the L3 vertebra is larger than the cervical and thoracic vertebrae above it. It features a thick body and a spinous process that projects backward, providing attachment points for muscles and ligaments. Proper alignment and health of the L3 vertebra are essential for overall spinal function and mobility.