Dartos
The dartos fascia is a fat-free layer of smooth muscular fiber outside the external spermatic fascia but below the skin. It is a continuation of Scarpa's fascia, which is a fatty layer of the subcutaneous tissue in the abdominal wall. The wrinkled (rugose) appearance of the scrotum is due to this layer of fascia.
Gender differences
- 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 farther.
- In females, the same muscle fibers are less well developed and termed dartos muliebris, lying beneath the skin of the labia majora.
- It receives innervation from postganglionic sympathetic nerve fibers arriving via the ilioinguinal nerve and the posterior scrotal nerve. (http://anatomy.med.umich.edu/gastrointestinal_system/inguinal_tables.html)
Function
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.
Related terms
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.
Additional images
External links
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