This chapter discusses affections of sciatic nerve. The sciatic nerve is the largest single nerve in the human body. It runs from each side of the lower spine through deep in the buttock into the back of the thigh and all the way down to the foot. It serves a vital role in connecting the spinal cord with the leg and foot muscles. Sciatica is commonly caused by some type of compression of a spinal nerve in the lower back. The medical term for sciatica is lumbar radiculopathy, or radicular pain, indicating that the symptoms originate with a radicular nerve in the spine. Clinical Features, Examination, and treatment of sciatic nerve are also discussed in this chapter.