Variations in the Anatomy of the Sciatic Nerve Bifurcation and its Relationship to the Musculus Piriformis: A Cadaveric Dissection Study

International Journal of Anatomy and Physiology | Vol. 15, No. 9, September 2026 | pp. 086–098

DOI: 10.46882/2026/IJAP/000175

Article Type: Original Research Article

Title: Variations in the Anatomy of the Sciatic Nerve Bifurcation and its Relationship to the Musculus Piriformis: A Cadaveric Dissection Study

Names of Authors: Carlos M. Gutierrez¹, Sofia A. Rodriguez²

Authors’ Affiliations: ¹Department of Morphological Sciences, Faculty of Medicine, University of Buenos Aires, Buenos Aires, Argentina; ²Department of Anatomy, Faculty of Medical Sciences, National University of La Plata, La Plata, Argentina

Abstract:
The sciatic nerve typically exits the pelvis through the greater sciatic foramen below the piriformis muscle before dividing into the tibial and common peroneal nerves near the apex of the popliteal fossa. Variations in this branching pattern and its relationship with the piriformis muscle can result in piriformis syndrome or unexpected nerve injuries during gluteal surgeries. This study evaluated these anatomical patterns in 80 formalized human cadaveric lower limbs (40 left and 40 right sides) using standard dissection techniques. The variations were classified according to the Beaton and Anson classification system. Group A, showing a normal undivided sciatic nerve passing completely below the piriformis muscle, was observed in 82.5% of cases (n = 66). High divisions of the sciatic nerve were recorded in 17.5% of limbs (n = 14). Among these variations, Beaton and Anson Type B (where the common peroneal nerve pierces the piriformis and the tibial nerve passes below it) was the most frequent, appearing in 11.25% of specimens (n = 9). Type C (common peroneal nerve passing above and tibial nerve below the muscle) was seen in 3.75% of cases (n = 3), while Type D (an entirely undivided nerve piercing the piriformis muscle) was observed in 2.5% of cases (n = 2). No statistically significant differences were noted between the left and right sides. These findings demonstrate that variations predisposing individuals to nerve compression are present in a notable proportion of the population.

Keywords: Sciatic Nerve, Piriformis Muscle, Anatomical Variations, High Division, Piriformis Syndrome, Cadaveric Dissection

Manuscript Timeline: Received: June 23, 2026; Revised: August 04, 2026; Accepted: August 21, 2026; Published: September 18, 2026

Citation: Gutierrez C.M., & Rodriguez S.A. (2026). Variations in the Anatomy of the Sciatic Nerve Bifurcation and its Relationship to the Musculus Piriformis: A Cadaveric Dissection Study. International Journal of Anatomy and Physiology, 15(9), 086–098. DOI: 10.46882/2026/IJAP/000175

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