The piriformis is a small, pear-shaped muscle located in the buttock region, beneath the larger gluteal muscles. It plays a crucial role in the movement of the hip joint, helping to rotate the thigh outward and stabilize the pelvis during activities like walking and running. The piriformis muscle is also significant because it runs close to the sciatic nerve, which can sometimes lead to a condition known as piriformis syndrome. This occurs when the muscle irritates or compresses the nerve, causing pain, tingling, or numbness in the buttocks and down the leg.