 The human foreskin contains a sheath of muscle tissue just below the skin, formerly known as the "peripenic muscle" and now called the dartos fascia, most of which is contained in the foreskin.Elastic fibers are contained in the dartos fascia, which form a whorl at the tip of the foreskin.The whorl of fibers acts as a sphincter in infants, which opens to allow the passage of urine, but closes to protect the glans penis from foreign matter and contaminants.