Dartos

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Dartos muscle
Gray1143.png
The scrotum. (Label for Dartos is at bottom left.)
Gray1144.png
The scrotum. (Label for Dartos is at bottom left.)
Name
Dartos
Latin
Tunica dartos
Origin
Subcutaneous tissue of scrotum, superficial to superficial fascia (Colles)
Insertion
Skin and midline raphé of scrotum
Blood
Artery of Duffy [This information needs a citation or reference.]
Nerve
Genital branch of genitofemoral nerve
Action
Corrugates the scrotum
Antagonist

The dartos fascia or simply dartos is a layer of connective tissue found in the skin of the penile shaft, foreskin, and scrotum.[1] The penile portion is referred to as the superficial fascia of penis or the subcutaneous tissue of penis,[2] while the scrotal part is the dartos proper. In addition to being continuous with itself between the scrotum and the penis, it is also continuous with Colles fascia of the perineum and Scarpa's fascia of the abdomen.[1]

It lies just below the skin, which places it just superficial to the external spermatic fascia in the scrotum and to Buck's fascia in the penile shaft.

In the scrotum, it consists mostly of smooth muscle.[3] The tone of this smooth muscle is responsible for the wrinkled (rugose) appearance of the scrotum.[1]

It receives innervation from postganglionic sympathetic nerve fibers arriving via the ilioinguinal nerve and the posterior scrotal nerve.

Function

In the penis, the loose attachment of the dartos fascia to Buck's fascia is responsible for the high degree of mobility of the penile skin over the underlying tissue.[1] It is also responsible for carrying the blood supply of the penile skin, a longitudinally-coursing anastomotic network of vessels that arise from the external pudendal vessels.[1]

In the scrotum, 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.

The dartos fascia keeps the foreskin close to the glans penis throughout life.[4] In infancy, the dartos fascia operates as a one-way check valve at the tip of the foreskin, allowing urine to pass out, but prohibiting the entry of foreign matter and pathogens.[5]

There is an increase in elastic fibers with increasing maturity that allows the foreskin to become retractable by adulthood and glide freely back and forth.

Related terms

Etymology:

Derived from the Greek δέρνω/derno (beat, flog) and/or δέρμα/derma (skin), meaning "that which is skinned or flayed", possibly due to its appearance.[6]

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

See also

References

  1. a b c d e REFbook Campbell: In: Alan J. Wein (ed.): Campbell-Walsh Urology. Philadelphia: Elsevier Saunders. ISBN 978-1-4160-6911-9.
  2. Terminologica Anatomica 98
  3. Gray's 16th Edition
  4. REFjournal Lakshmanan, S. / S. Prakash (1980): Human prepuce: some aspects of structure and function, in: Indian J Surg. 44:134-7. Retrieved 29 September 2019. Quote: "The normal tone of the muscle arranged in this fashion and supplemented by elastic tissue offers a legitimate explanation for the close fit of the prepuce through the ages."
  5. REFjournal Fleiss, P.M. / F,M, Hodges / R..S. Van Howe (1 October 1998): Immunological functions of the human prepuce, in: Sex Trans Inf. 74 (5):364-7, PMID. Retrieved 1 October 2019. Quote: ""The sphincter action of the preputial orifice functions like a one way valve, blocking the entry of contaminants while allowing the passage of urine.""
  6. REFweb Catlin, B (2008). "Etymology of Abdominal Wall and Inguinal Terms", Darmouth. Retrieved 1 October 2019.