Piriformis syndrome – The piriformas muscle rests in the back of the thigh under the buttocks. It is a small muscle that traverses the short axis of the thigh from the pelvis to the femur. The sciatic nerve exits the pelvis under it. Occasionally, the sciatic nerve will go right through this muscle. The muscle can have a thick fibrous band within its substance that can occasionally irritate the sciatic nerve. This muscle has historically been unfairly blamed for the source of many patients’ sciatica. The only reason it had been implicated in the past was because it happened to be right in the path of the sciatic nerve. Before the discovery of herniated discs that compress nerve roots, early anatomists used deduction to conclude that the nerve could be compressed by this muscle. This theory made sense as the nerve itself commonly refers pain to this region and will locally be very tender to touch. This syndrome is however, exceedingly rare and very often over-diagnosed. Most patients with this “syndrome” have nerve pain from the lumbar spine that refers to this muscle.