The dartos is a layer of smooth muscular fiber outside the external spermatic fascia but below the skin. Sometimes jokingly referred to as King Dartos given the nature of its function in the male specimen.
- In males it is termed tunica dartos and lies beneath the skin of the scrotum. In older males the dartos muscle loses its tone, and tends to cause the scrotum to be smoother and to hang down further.
- In females, the same muscle fibers are less well developed and termed dartos muliebris, lying beneath the skin of the labia majora.
The tunica dartos acts to regulate the temperature of the testicles, which promotes spermatogenesis. It does this by expanding or contracting to wrinkle the scrotal skin.
- Contraction reduces the surface area available for heat loss, thus reducing heat loss and warming the testicles.
- Conversely, expansion increases the surface area, promoting heat loss and thus cooling the testicles.
The dartos muscle works in conjunction with the cremaster muscle to elevate the testis but should not be confused with the cremasteric reflex.
Some dartos-related terms:
- dartoic (dar·to·ic) (dahr-to'ik) of the nature of a dartos; having a slow, involuntary contractility like that of the dartos.
- dartoid (dar·toid) (dahr'toid) resembling the dartos.
|Male reproductive system|
|Scrotum||layers (skin, Dartos, External spermatic fascia, Cremaster/Cremasteric fascia, Internal spermatic fascia) • Perineal raphe • Spermatic cord|
|Testes||layers (Tunica vaginalis, Tunica albuginea) • Appendix • Mediastinum • Lobules • Septa • Leydig cell • Sertoli cell • Blood-testis barrier|
|Spermatogenesis||Spermatogonium • Spermatocytogenesis • Spermatocyte • Spermatidogenesis • Spermatid • Spermiogenesis • Spermatozoon|
|seminal tract||Seminiferous tubules (Tubuli seminiferi recti, Rete testis, Efferent ducts) • Epididymis (Appendix) • Vas deferens (Ampulla) • Ejaculatory duct|
|urinary tract||Internal urethral orifice • Urethra (Prostatic, Intermediate, Spongy, Navicular fossa) • External urethral orifice|
|accessory glands||Seminal vesicles (Excretory duct of seminal gland) • Prostate (Urethral crest/Seminal colliculus/Prostatic utricle/Ejaculatory duct, Prostatic sinus/Prostatic ducts) • Bulbourethral glands|
|Penis||root (Crus, Bulb, Fundiform ligament, Suspensory ligament) • body (Corpus cavernosum, Corpus spongiosum) • glans (Foreskin, Frenulum, Corona) • fascia (superficial/subcutaneous, deep/Buck's) • Tunica albuginea - Septum of the penis|