Final answer:
The piriformis muscle is often responsible for the compression of the sciatic nerve, leading to sciatica. This condition involves pain, numbness, or tingling radiating from the lower back to the leg due to irritation of the nerve that passes beneath or through the piriformis muscle.
Step-by-step explanation:
The external hip rotator often involved in the compression of the sciatic nerve is the piriformis muscle. This muscle is located in the gluteal region and is one of the muscles that enable the lateral rotation of the femur at the hip. The sciatic nerve passes beneath the piriformis muscle as it travels from the sacral plexus, and in some individuals, through the piriformis muscle. When the piriformis muscle becomes tight or spasms, it can compress or irritate the sciatic nerve, leading to a painful condition known as sciatica.
Sciatica results from the inflammation or compression of the sciatic nerve, which is a systemic nerve extending from the sacral plexus and is a combination of the tibial and fibular nerves. It runs across the hip joint and gluteal region into the upper posterior leg. Symptoms of sciatica can include sharp pain, numbness, or tingling that radiates from the lower back down to the leg. Treatment may involve physical therapy, medications, or in severe cases, surgery.