The piriformis muscle is a pyramid-shaped muscle in the gluteal region. It originates at the anterior sacrum, the lowest portion of the spine, and the superior margin of the greater sciatic notch, extends through the greater sciatic foramen of the pelvis, and attaches to the greater trochanter of the femur. The piriformis mucle lies parallel to and beneath the gluteus maximus.
The common peroneal nerve often runs through the piriformis muscle, and in about 15% of the population, the sciatic nerve does as well. In most people, the sciatic nerve runs underneath the piriformis muscle. In either case, the piriformis muscle can sometimes exert pressure on the sciatic nerve, causing a pain called sciatica, though the condition is more common in those whose sciatic nerve runs through the muscle.
Piriformis symdrome is a condition characterized by pain, numbness, or a tingling sensation in the buttocks caused by irritation of the sciatic nerve by the piriformis mucle. The symptoms may also extend down the leg. Piriformis syndrome may result from a person's natural anatomy or from overuse or strain of the piriformis muscle. Inactive gluteal muscles and overactive hip flexor muscles can also contribute to the syndrome, as the piriformis muscle becomes overdeveloped in order to compensate. The condition is more common in people who sit down for extended hours, especially with a large wallet in their back packet, and in athletes like cyclists and runners who fail to include lateral exercises and stretching in their regimen.
Pain or strain in the piriformis muscle can be treated by massage, stretching exercises, an physical therapy, and core-strengthening exercises. In extreme cases of piriformis syndrome, anti-inflammatory or corticosteroid injections or ultrasound therapy can be helpful. Stretching exercises for the prirformis muscle can be performed by lying on ones back and pulling one knee at a time into ones chest. Grasp the knee with one hand and the ankle with the other, and leading with the ankle, bend the knee toward the ankle of the opposite foot. Stretch slowly and gently and do not force the stretch.
A similar stretch can be performed by lying on ones back, bending one knee, and placing the foot outside the other leg. Bend the knee gently across the midline of the body. For a final exercise, lying flat on your back, bend both knees and cross one over the other, then, grasping below the lower knee, pull both knees into the chest towards the shoulder on the side of the lower knee. For all of these stretches, make sure not to stretch to the point of discomfort. Hold each for 30 seconds and come out of the stretch slowly and gently.