The dartos fascia (or, simply, dartos) is a layer of connective tissue found in the penile shaft, foreskin, scrotum, and labia. More specifically, the dartos lies just below the skin, which places it just superficial to the external spermatic fascia in the scrotum and to Buck's fascia in the penile shaft. In the scrotum, it consists mostly of smooth muscle. The tone of this smooth muscle is responsible for the wrinkled (rugose) appearance of the scrotum. In females, the same muscle fibers are less well developed and termed dartos muliebris, lying beneath the skin of the labia majora. The dartos fascia receives innervation from postganglionic sympathetic nerve fibers arriving via the ilioinguinal nerve and the posterior scrotal nerve.