Many medical manuals, advertisements or popular science books compare sciatica as a disease with lumbar disc herniation, lumbar spinal stenosis, acute lumbar sprain, chronic lumbar strain and other diseases. Our orthopedic professionals believe that this is not only uncritical but also misleading to patients, so it is necessary to give it a “proper name”. The sciatic nerve is the longest nerve in the body, issued from the nerve root of the lumbar segment of the spinal cord, penetrated by the pear-shaped muscle below the buttocks, distributed in the back of the thighs, as well as the calves and feet, commanding muscle movement and conducting skin sensation. In normal people, there is one on the left and one on the right. Of the five lumbar vertebrae, the fourth and fifth lumbar vertebrae below are the most heavily burdened and have the greatest mobility, and are prone to degeneration and aging. Long-term strain or sudden sprain can cause the lumbar intervertebral disc to protrude to the side and back. After the lumbar disc protrudes, it compresses the sciatic nerve root, causing pathological changes such as congestion, edema and even adhesions. The pain on the herniated side of the lumbar area radiates through the buttocks to the back of the thighs, up to the calves and feet, and sometimes there is numbness, which is aggravated by coughing. This symptom is sciatica. It is just a symptom like a fever. Pathological changes such as lumbar disc herniation or lumbar spinal stenosis are the cause of sciatica, just as the cause of fever is a cold, pneumonia or meningitis, etc. Although there are many causes of sciatica, the most common one is lumbar disc herniation, and most of them are herniated discs between the 4th and 5th lumbar vertebrae or between the 5th lumbar vertebrae and the sacrum. Thus, in the vast majority of cases, sciatica may be a lumbar disc herniation. In orthopedic clinics, we have found that in addition to lumbar disc herniation that can cause sciatica, there are many other diseases that can also cause this symptom. The more common ones are lumbar spinal stenosis, lumbar spondylolisthesis, pear-shaped muscle syndrome, ankylosing spondylitis and lumbar spinal tumor. However, sometimes, some informal hospitals and non-orthopedic physicians blindly treat patients with sciatica symptoms with a diagnosis of “sciatica” without investigating the deeper pathological causes, which is actually unscientific and irresponsible. It is important to point out that lumbar disc herniation does not necessarily manifest as sciatica. There are five lumbar vertebrae in the human body, corresponding to this, there are five pairs of lumbar nerve roots, part of the 4th lumbar nerve root, the 5th lumbar nerve root and the 1st, 2nd and 3rd sacral nerve roots form the sciatic nerve, while the 2nd and 3rd nerve roots and some fibers of the 4th lumbar nerve are only involved in the femoral nerve distributed in front of the thigh, not in the sciatic nerve, thus the 1st to 2nd or 2nd to 3rd or 3rd to 4th lumbar disc herniation may cause symptoms of compression of the femoral nerve. It usually manifests as weakness in lifting the leg and dull sensation of the skin in the anterior or medial thigh; there are also some patients with lumbar 5 to sacral 1 disc herniation who do not have sciatica. In some cases, the early onset of the disease or the whole course of the disease may only be manifested as lumbar pain, and in others, intermittent claudication, walking a few hundred meters, then feeling soreness and weakness in the lower limbs, and having to rest or bend and squat for a while to continue walking; in some cases, the patient only feels coldness in the limbs; in some severe cases, paralysis, inability to move the lower limbs, and incontinence of urination and defecation.