Where does lumbar disc herniation occur? Let's first discuss what a lumbar disc is. A lumbar disc is a fibrous pad located between the upper and lower vertebrae, which can be understood as a joint between the two vertebrae. Its outer layer is made up of a dense fibrous ring, formed in different combinations and arrangements, with a nucleus pulposus in the middle, which primarily functions to bear pressure from various directions and disperse it. Lumbar disc herniation occurs when, for various reasons such as aging, trauma, or pathological changes, the lumbar disc protrudes. If the protrusion does not break through the fibrous ring, it is called bulging. If it compresses and causes the fibrous ring to rupture, it is called herniation. Thus, the herniation can protrude backward, upward, or forward; however, it is mostly the backward protrusion that can cause symptoms by compressing nearby tissues, such as the spinal cord, blood vessels, and nerve roots.