Sciatic and Posterior Femoral Cutaneous Nerve Anomalies and Their Clinical Implications for Sciatica and Piriformis Syndrome: A Cadaveric Case Report

The sciatic nerve (SN), the largest nerve in the human body, normally exits the pelvis inferior to the piriformis muscle (PM) before dividing into its two terminal branches, the tibial nerve (TN) and the common fibular nerve (CFN). Variations in the anatomy of the SN and the posterior femoral cutaneous nerve (PFCN) may occur during embryologic development and can have important clinical implications, including piriformis syndrome, sciatica, and increased susceptibility to iatrogenic injury. This case report describes a rare concurrent variation of both the SN and PFCN identified during routine cadaveric dissection. During a pedagogical dissection of the gluteal region in an 84-year-old female cadaver, notable anomalies in the formation and course of these nerves were observed. Instead of emerging as a single trunk, the CFN and TN exited the pelvis independently through the greater sciatic foramen. The CFN pierced the PM, dividing it into two muscular heads before converging with the TN approximately one inch inferior to the muscle to form a single SN trunk. The TN exited inferior to the PM and followed a relatively typical course. Additionally, the PFCN exited the pelvis as separate nerve roots, with the most lateral root piercing the PM while the remaining roots passed inferior to the muscle. These findings correspond to a unilateral type 2(B) variation of the SN according to the Beaton and Anson classification. Anatomical variations of the SN and PFCN are clinically significant because they may predispose individuals to nerve entrapment syndromes such as piriformis syndrome and may increase the risk of nerve injury during procedures, including hip arthroplasty, gluteal injections, and proximal hamstring repair. Recognition and documentation of these variants are essential for improving diagnostic accuracy, guiding surgical planning, and supporting more individualized approaches to patient care.