ABSTRACT
The aim of this study was to examine the variation of the sacral plexus in Thais in terms of its origin, branches, and variation in each branch. Anatomical dissections were conducted in 150 halves of formalin-embalmed cadavers. All preserved cadavers were Thais, ranging in age from 35 to 85 years old, 86 males and 64 females. The sacral plexus was markedly comprised of the fourth lumbar to fourth sacral ventral rami (L4-S4) in 98.67% of the plexuses (or 148 cases) except for two plexuses (1.33% of the plexuses) those were derived from the ventral rami of the fourth lumbar to fifth sacral ventral rami (L4-S5). The sacral plexus, lying on the posterior wall of the lesser pelvis to the piriformis muscle, has nine named branches. Six of these are distributed to the buttock and lower lomp, including 1) Nerve to the Quadratus Femoris and Gemellus Inferior, 2) Nerve to the Obturator Internus and Gemellus Inferior, 3) Superior Gluteal, 4) Inferior Gluteal, 5) Posterior Femoral Cutaneous and 6) Sciatic. The other branches supply structures belonging to the pelvis, including 7) Nerve to the Piriformis, 8) Pudendal and 9) Pelvic Splanchnic. The variant of origination and formations of all branches occur on both side. However, the anatomic variability of the plexuses was not statistically different with regard to either side or gender. The results from this study provided additional information and new insights into the sacral plexus in terms of its origins, branches, and variations of each branch that might be useful in medicine, anesthesia, surgery and physical therapy.