The posterior cutaneous nerve of the thigh is formed by contributions from S1 to S3 and leaves the pelvic cavity through the greater sciatic foramen inferior to the piriformis muscle (Fig. 6.36 and Table 6.1). It passes vertically through the gluteal region deep to the gluteus maximus and enters the posterior thigh and innervates: a longitudinal band of skin over the posterior aspect of the thigh that continues into the upper leg, and skin over the gluteal fold, over the upper medial part of the thigh and in the adjacent regions of the perineum.