The dartos fascia, dartos tunic or simply dartos is a layer of

connective tissue Connective tissue is one of the four primary types of animal tissue, a group of cells that are similar in structure, along with epithelial tissue, muscle tissue, and nervous tissue. It develops mostly from the mesenchyme, derived from the mesod ...

found in the penile shaft,

foreskin In male Human body, human anatomy, the foreskin, also known as the prepuce (), is the double-layered fold of Human skin, skin, Mucous membrane, mucosal and Muscle tissue, muscular tissue at the distal end of the human penis that covers the glans ...

and

scrotum In most terrestrial mammals, the scrotum (: scrotums or scrota; possibly from Latin ''scortum'', meaning "hide" or "skin") or scrotal sac is a part of the external male genitalia located at the base of the penis. It consists of a sac of skin ...

. 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 The membranous layer of the superficial fascia of the perineum (Colles' fascia) is the deeper layer ( membranous layer) of the superficial perineal fascia. It is thin, aponeurotic in structure, and of considerable strength, serving to bind down t ...

of the perineum and

Scarpa's fascia The fascia of Scarpa is the deep membranous layer ''(stratum membranosum)'' of the superficial fascia of the abdomen. It is a layer of the anterior abdominal wall. It is found ''deep'' to the fascia of Camper and ''superficial'' to the external ...

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 scro ...

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

smooth muscle Smooth muscle is one of the three major types of vertebrate muscle tissue, the others being skeletal and cardiac muscle. It can also be found in invertebrates and is controlled by the autonomic nervous system. It is non- striated, so-called bec ...

. 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 In primates, and specifically in humans, the labia majora (: labium majus), also known as the outer lips or outer labia, are two prominent Anatomical terms of location, longitudinal skin folds that extend downward and backward from the mons pubis ...

. The dartos fascia receives innervation from postganglionic sympathetic nerve fibers arriving via the

ilioinguinal nerve The ilioinguinal nerve is a branch of the first lumbar nerve (L1). It separates from the first lumbar nerve along with the larger iliohypogastric nerve. It emerges from the lateral border of the psoas major just inferior to the iliohypogastric, ...

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 dartos fascia acts to regulate the

temperature Temperature is a physical quantity that quantitatively expresses the attribute of hotness or coldness. Temperature is measurement, measured with a thermometer. It reflects the average kinetic energy of the vibrating and colliding atoms making ...

of the

testicle A testicle or testis ( testes) is the gonad in all male bilaterians, including humans, and is Homology (biology), homologous to the ovary in females. Its primary functions are the production of sperm and the secretion of Androgen, androgens, p ...

s, which promotes

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

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

surface area The surface area (symbol ''A'') 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 d ...

available for heat loss, thus reducing

heat In thermodynamics, heat is energy in transfer between a thermodynamic system and its surroundings by such mechanisms as thermal conduction, electromagnetic radiation, and friction, which are microscopic in nature, involving sub-atomic, ato ...

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 The cremaster muscle is a paired structure made of thin layers of striated and smooth muscle that covers the testicles and the spermatic cords in human males. It consists of the lateral and medial parts. Cremaster is an involuntary muscle, respo ...

to elevate the

testis A testicle or testis ( testes) is the gonad in all male bilaterians, including humans, and is Homology (biology), homologous to the ovary in females. Its primary functions are the production of sperm and the secretion of Androgen, androgens, p ...

but should not be confused with the

cremasteric reflex The cremasteric reflex is a superficial (i.e., close to the skin's surface) reflex observed in human males. This reflex is elicited by lightly stroking or poking the superior and medial (inner) part of the thigh—regardless of the direction of ...

. 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 Scrotum