The sciatic nerve is the largest nerve in the human body. The sciatic nerve originates from several nerves in your lower back, much like small streams coming together to form a river. These nerves extend from the lumbar (lower) spine and come together between the muscles of each buttock to form the sciatic nerve. The sciatic nerve then travels down each leg before dividing into smaller branches. The sciatic nerve carries movement signals down to the muscles of the leg and sends pain, temperature, and other sensory signals up to the brain. Symptoms of “sciatica” radiate along the same path.