Dartos

The tunica dartos ( " skinned " of gr dartos, " like raw meat " ) is a thin layer of smooth muscle fibers under the skin of the scrotum. It is used for temperature regulation of the testes. Stretches the muscle layer along the skin of the scrotum is wrinkled and thus the surface area is smaller, which means less body heat is lost, so the testicles are warmer. Conversely, the relaxation of the tunica dartos to a larger surface of the scrotum and thus to a cooling of the testes. The testicle lifter muscle is used in a similar way of regulating the temperature of the testicles.

When older man, the muscle tone of the tunica dartos may decrease, so that the scrotum hangs lower down.

The innervation of the tunica dartos is via sympathetic fibers of the genital branch of the genitofemoral nerve.