The dartos is a smooth muscle layer in the scrotal skin that contracts to rugose and thicken the scrotum in cold conditions, complementing the cremaster muscle's testicular elevation. Unlike the cremaster (striated — under reflex control), the dartos is smooth muscle under autonomic control. The dartos fascia is used in hypospadias repair to provide a second waterproof layer over urethral reconstruction.
| Origin | Superficial perineal fascia (Colles' fascia) at the base of the scrotum |
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| Insertion | Scrotal skin — the dartos is fused to the dermis throughout the scrotum with no bony attachment |
| Nerve Supply | Sympathetic fibres via the ilioinguinal nerve and genital branch of genitofemoral nerve |
| Blood Supply | Scrotal branches of the perineal artery |
| Actions | Wrinkles and contracts the scrotal skin in cold conditions (sympathetically mediated); Divides the scrotum into two compartments via the scrotal septum |
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In fournier's gangrene (necrotising fasciitis of the perineum and scrotum), the dartos fascia is one of the primary tissue planes involved. Aggressive debridement down to the dartos layer is required. In hypospadias repair, the dartos flap provides the second layer cover over the urethroplasty to prevent fistula formation.
The dartos wrinkles are visible as the scrotal rugosity — more prominent in cold conditions when the dartos contracts.
Necrotising fasciitis of the dartos fascia and scrotal layers requiring emergency radical debridement and broad-spectrum antibiotics.
