The dartos fascia or simply dartos is a layer of

connective tissue Connective tissue is one of the four primary types of animal tissue, along with epithelial tissue, muscle tissue, and nervous tissue. It develops from the mesenchyme derived from the mesoderm the middle embryonic germ layer. Connective tiss ...

found in the penile shaft,

foreskin In male human anatomy, the foreskin, also known as the prepuce, is the double-layered fold of skin, mucosal and muscular tissue at the distal end of the human penis that covers the glans and the urinary meatus. The foreskin is attached to the ...

scrotum The scrotum or scrotal sac is an anatomical male reproductive structure located at the base of the penis that consists of a suspended dual-chambered sac of skin and smooth muscle. It is present in most terrestrial male mammals. The scrotum co ...

and

labia The labia are part of the female genitalia; they are the major externally visible portions of the vulva. In humans, there are two pairs of labia: the ''labia majora'' (or the outer labia) are larger and thicker, while the '' labia minora'' are fo ...

. The penile portion is referred to as the superficial fascia of penis or the subcutaneous tissue of penis, 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. The dartos lies just below the skin, which places it just superficial to the external spermatic fascia in the scrotum and to

Buck's fascia Buck's fascia (deep fascia of the penis, Gallaudet's fascia or fascia of the penis) is a layer of deep fascia covering the three erectile bodies of the penis. Structure Buck's fascia is continuous with the external spermatic fascia in the scrotu ...

in the penile shaft. In the scrotum, it consists mostly of

smooth muscle Smooth muscle is an involuntary non- striated muscle, so-called because it has no sarcomeres and therefore no striations (''bands'' or ''stripes''). It is divided into two subgroups, single-unit and multiunit smooth muscle. Within single-unit ...

. The tone of this smooth muscle is responsible for the wrinkled (rugose) appearance of the scrotum. In females, the same muscle fibers are less well developed and termed ''dartos muliebris,'' lying beneath the skin of the

labia majora The labia majora (singular: ''labium majus'') are two prominent longitudinal cutaneous folds that extend downward and backward from the mons pubis to the perineum. Together with the labia minora they form the labia of the vulva. The labia maj ...

. The dartos fascia 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. 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. In the scrotum, the tunica dartos acts to regulate the

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...

of the

testicle A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testoste ...

s, which promotes

spermatogenesis Spermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testis. This process starts with the mitotic division of the stem cells located close to the basement membrane of the tubu ...

. It does this by expanding or contracting to wrinkle the scrotal skin. * Contraction reduces the

surface area The surface area of a solid object is a measure of the total area that the surface of the object occupies. The mathematical definition of surface area in the presence of curved surfaces is considerably more involved than the definition of ...

available for heat loss, thus reducing

heat In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is ...

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 A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testostero ...

but should not be confused with the cremasteric reflex. The dartos fascia keeps the foreskin close to the glans penis throughout life. 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. 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. 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

File:Gray1145.png, Transverse section through the left side of the scrotum and the left testis. File:Slide9eee.JPG, Dartos File:Penis_cross_section.svg

References

{{Authority control Mammal reproductive system Human reproduction Fascia