What’s going on with a herniated lumbar disc and a numb leg all the time? To answer this question, it is important to understand what a herniated lumbar disc is and how it develops. The human body has a flexible cartilage cushion between the lumbar vertebrae called the lumbar disc, and the structure is composed of two layers of fibrous rings on the outside and the medial nucleus pulposus. As we age, the intervertebral disc undergoes degenerative changes, and on the basis of metamorphosis, if there is a field action the fibrous ring will break and the nucleus pulposus will protrude, which will compress the nerve roots on both sides and cause numbness or pain in the legs. When the nucleus pulposus compresses the sinus nerve in the back, pain in the lower back will occur.