The L4 vertebra is one of the five lumbar vertebrae located in the lower back. 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. The L4 vertebra is situated between the L3 vertebra and the L5 vertebra. It has a larger and thicker structure compared to the cervical and thoracic vertebrae, which helps it withstand the stresses of daily activities. Proper alignment and health of the lumbar vertebrae are essential for overall spinal health.