Piriformis Syndrome

The piriformis muscle extends from the inner surface of the sacral bone, triangular-shaped bone at the bottom of the spine, and is inserted into the femur, the thigh bone.  

Occasionally the piriformis muscle may become irritable and go into spasm and may be the cause of sciatic type pain in some cases of sciatica. It is possible to experience buttock pain, referred pain to the thigh of frank sciatic pain, pain on sitting on the affected buttock and difficulty climbing stairs or inclines.