Posterior femoral cutaneous nerve
The posterior femoral cutaneous nerve provides innervation to the back side of the leg and thigh area, as well as to the perineal skin surface.
It is a small sciatic nerve that originates partially from the dorsal and ventral divisions of the nerves in the sacrum. It exits the pelvic region via an opening known as the greater sciatic foramen. From there, it traverses below the gluteus maximus muscle and above the elongated top of the biceps femoris muscle in the rear portion of the thigh, before finally entering the deep fascia.
It is called the cutaneous nerve because all its branches pertain to the skin. These branches are spread throughout the skin of the perineum, the buttocks region, and the posterior (rear) parts of the leg and thigh. The posterior femoral cutaneous nerve includes a number of nerve filaments that spread out and are distributed over the posterior part of the leg and thigh.