Dartos

Dartos
The scrotum. (Label for Dartos is at bottom left.)
The scrotum. (Label for Dartos is at bottom left.)
Gray's	subject #258 1238
Origin
Insertion
Artery
Nerve	Genital branch of genitofemoral nerve
Actions

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 membranous 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 further.
• In females, the same muscle fibers are less well developed and termed dartos muliebris, lying beneath the skin of the labia majora.

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

Transverse section through the left side of the scrotum and the left testis.

External links

• LUC dart
• -711327667 at GPnotebook