Unusual accessory piriformis muscle: A case report

In human anatomy, piriformis muscle and peripheral nerve variants may represent an unrecognized etiology. These variations in the gluteal region may cause entrapment of the sciatic nerve and induce to the piriformis syndrome. We present a case of accessory piriformis muscle accompanying to high divisions of sciatic nerve, unusual course of nerves and fusion of the piriformis muscle with gluteus medius in the left gluteal region of a 64-year-old male cadaver. The nerves which are originating from dorsal part of the sacral plexus, inferior gluteal nerve, common fibular part of the sciatic nerve and posterior femoral cutaneous nerve are located between the piriformis and accessory piriformis muscles make this case the most interesting of its kind. Awareness of these variations may prove to be useful for surgeons during the surgery of the gluteal region and the clinician when treating patients with buttock pain. Additionally, the possible role of aberrant anatomical variations of the related region in causing piriformis syndrome must be taken into consideration as one of the contributing factors.