Posterior femoral cutaneous nerve

Plexus: Lumbosacral
Roots: S1S2S3S4
Origin: Dorsal divisions of S1, S2 and ventral divisions of S3, S4

Sensory innervation:

Branch: Posterior femoral cutaneous nerve
Roots: S1S2S3S4
Branch: Inferior cluneal nerves
Roots: S1S2S3S4