Spine levels—S2-S5

Penis

The penis is innervated by the pudendal N, arising from the lower sacral plexus.

The scrotum and testicle are innervated by the ilioinguinal and genitofemoral nerves, branches from around L1 (this is why renal colic is referred to the testicle, also why you scratch the scrotum to get the cremasteric reflex).