A Rare Anatomical Variation of Sciatic Nerve and its Relationship with Piriformis Muscle

Sciatic nerve is the thickest nerve of the body which is formed by ventral branches of L4, L5, S1, S2 and S3 of spinal nerves as a part of sacral plexus in pelvis. It leaves the pelvis via the greater sciatic foramen below piriformis muscle and descends between the greater trochanter and ischial tuberosity, along the back of the thigh and dividing into the tibial and common peroneal (fibular) nerves, at a varying level proximal to the knee. In addition, the piriformis muscle, the intrapelvic muscle, may compress the sciatic nerve and causes the piriformis syndrome. At present case, sciatic nerve was divided in the pelvis and left the pelvis via supera piriformis, inferapiriformis and interapiriformis. According to the reports about the variations of sciatic nerve regarding to its leaving and dividing point, it is important in surgical operations, muscular injection in gluteal regions and piriformis syndrome.