A three-headed piriformis muscle: an anatomical case study and narrative review of literature.

The clinical importance of this work comes down to the fact that the aberrant PM may be the reason behind the piriformis syndrome and its associated symptoms. Moreover, knowledge regarding the variant anatomy of the PM is of immense importance to, e.g., anesthesiologists performing CT- or ultrasound-guided SN injection for local anesthesia, radiologists interpreting imaging studies, and surgeons, especially during posterior approaches to the hip and pelvis.