(1) Lumbar 3 to 4 disc herniation ① Involved nerve. Lumbar 4 or lumbar 5 nerve root. (2) Pain site. Low back, sacroiliac region, lateral thigh and anterior calf. ③ pressure pain point. Lumbar 3, lumbar 4 interspinous and paraspinous. ④Numbness site. Anterior medial calf and anterior knee joint. ⑤ Muscle strength change. Weakness of knee extension. ⑥Atrophic muscles. Quadriceps femoris. (vii) Reflex changes. Weak or absent knee reflex. (2) Lumbar 4 to 5 disc herniation ①Involved nerve. Lumbar 5 nerve root. (ii) Pain site. Sacroiliac region, thigh and lateral calf. (3) Pressure pain point a lumbar 4, lumbar 5 paraspinal. ④Numbness site. Anterolateral calf and medial dorsalis pedis and plantaris. ⑤ Muscle strength changes. Weakness of the dorsal extensor muscle of the bunion. ⑥Atrophic muscles. Anterolateral calf muscle group. (vii) Reflex changes. None. (3) Lumbar 5 to sacral I disc herniation ①Involved nerve. Sacral 1 nerve root. (ii) Pain site. Sacroiliac region, thigh, calf and lateral heel. ③ pressure pain point. Lumbar 5 sacral 1 paraspinal. ④Numbness site. Posterior lateral calf and dorsum of the foot including the lateral three toes. ⑤ Muscle strength changes. Weakness of bunion and plantar flexion of the foot. ⑥Atrophic muscles. Posterior calf muscle group. (vii) Reflex changes. Weak or absent Achilles tendon reflex. (4) Central type lumbar disc herniation ①Involved nerves. Cauda equina nerve from lumbar 4 to 5 and lumbar 5 to sacral 1. (2) Pain site. Low back, bilateral thighs and posterior calves. ③ pressure pain point. Lumbar 5 sacral 1 center ④Numbness site. Saddle area, bilateral thighs, posterior calves, soles of the feet and perineum. ⑤ Muscle strength changes. Weakness or paralysis of bladder and anal sphincter muscles, urinary and fecal dysfunction. (vi) Atrophic muscles. Uncertain. (vii) Reflex changes. Achilles tendon and anal reflexes disappear. [Key Tips] In clinical practice, the localization diagnosis of lumbar disc herniation is very meaningful. For example, if the patient’s imaging suggests two or more multi-segmental disc herniations, how to determine which herniated nucleus pulposus is responsible for the patient’s problem, or which herniated nucleus pulposus is causing the more serious problem. At this point, the localization diagnosis can be better determined.