What is the sciatic nerve?

(Sciatica is a condition involving pain, weakness, numbness, or tingling in the leg. It is caused by an injury to or compression of the sciatic nerve which branches down your back.The sciatic nerve is commonly injured by fractures of the pelvis, gunshot wounds, or other trauma to the buttocks or thigh. Prolonged sitting or lying with pressure on the buttocks may also injure it. )

The sciatic nerve is the longest nerve in your body; it runs from your lower back, through your buttock, down your leg.

The tibial and fibular nerves originate from spinal segments L4-S3. The two nerves come together and are referred to jointly as the sciatic (meaning hip) nerve. The sciatic nerve is the largest peripheral nerve in the body.They separate at the back of the knee. The tibial nerve supplies the posterior compartment of the leg and the fibular supplies the anterior and lateral compartments.
The sciatic nerve are nerve roots coming out of the spinal cord and into the lower back.