Dominic Stone
The dartos muscle is a sympathetically innervated dermal layer within the scrotum. It is composed of smooth muscle cells and is also referred to as the dartos fascia. The dartos muscle is responsible for regulating the temperature of the testicles, promoting spermatogenesis. It does this by expanding or contracting to wrinkle the scrotal skin, thereby increasing or reducing the surface area available for heat loss. The muscle also works in conjunction with the cremaster muscle to elevate the testis.
| Characteristics | Values |
|---|---|
| Definition | The dartos muscle is the scrotal part of the dartos fascia, composed of smooth muscle cells. |
| Location | The dartos muscle is located in the scrotum, the sac-like organ made of skin and muscles that houses the testes. |
| Function | The dartos muscle regulates the temperature of the testicles, promoting spermatogenesis. It does this by expanding or contracting to wrinkle the scrotal skin, thereby controlling heat loss. |
| Layers | The dartos muscle is part of the outer layer of the scrotum, which also includes the skin and superficial fascia. |
| Innervation | The dartos muscle is sympathetically innervated, distinct from the somatically innervated cremaster muscle. |
| Penis | In the penis, the dartos fascia keeps the foreskin close to the glans penis and is responsible for the high degree of mobility of the penile skin. |
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What You'll Learn
The dartos muscle is the scrotal part of the dartos fascia
The dartos muscle, also known as the tunica dartos, is the scrotal part of the dartos fascia. It is a thin, rugated fascial muscle composed of smooth muscle cells. The dartos muscle forms from the subcutaneous tissue of the scrotum and base of the penis, attaching to the scrotal skin and fibrous midline septum between the testes.
The scrotum is a sac-like organ that houses the testes and is located inferior to the penis in the pubic region. It is made up of two side-by-side fibromuscular pouches, each containing a testis, and is surrounded by various fibroelastic and muscular layers. The dartos muscle is the most prominent of these layers.
The primary function of the dartos muscle is to regulate the temperature of the testicles, which promotes spermatogenesis. It achieves this by expanding or contracting to wrinkle the scrotal skin. When the dartos muscle contracts, the surface area available for heat loss is reduced, thereby warming the testicles. Conversely, expansion of the dartos muscle increases the surface area, promoting heat loss and cooling the testicles.
The dartos muscle works in conjunction with the cremaster muscle to elevate the testis. However, it is important to distinguish between the functions of these two muscles. The cremasteric reflex is a distinct response, separate from the role of the dartos muscle in temperature regulation and elevation of the testes.
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It is composed of smooth muscle cells
The dartos muscle is a thin, rugated fascial muscle of the scrotum, composed of smooth muscle cells. It is also referred to as the dartos fascia or simply the dartos. The dartos muscle is the scrotal part of the dartos fascia. It forms from the subcutaneous tissue of the scrotum and the base of the penis, attaching to the scrotal skin and the fibrous midline septum between the testes. The dartos muscle is distinct from the somatically innervated cremaster muscle.
The dartos muscle is responsible for regulating the temperature of the testicles, promoting spermatogenesis. It does this by contracting and relaxing to wrinkle the scrotal skin, which either reduces or increases the surface area available for heat loss, thereby warming or cooling the testicles. This regulatory function is particularly important in ambient temperatures up to 30°C.
The tunica dartos is the most prominent muscular layer of the scrotum, a sac-like organ made of skin and muscles that houses the testes. The dartos layers are confluent between the testes, where they form the intertesticular septum. The scrotal skin contraction can be elicited by electric cutaneous stimulation of the thigh, and this dartos reflex is a test of lumbar sympathetic function.
In the penis, the dartos 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. In infancy, the dartos fascia operates as a one-way check valve at the tip of the foreskin, allowing urine to pass out while prohibiting the entry of foreign matter and pathogens.
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It regulates testicle temperature, promoting spermatogenesis
The dartos muscle, also known as the dartos fascia, is a thin, rugated fascial muscle of the scrotum made of smooth muscle cells. It is the most prominent layer of the scrotum, which is a sac-like organ that houses the testes. The scrotum is located inferior to the penis in the pubic region and is made up of two side-by-side fibromuscular pouches, each containing a testis.
The dartos muscle plays a crucial role in regulating the temperature of the testicles, which in turn promotes spermatogenesis. This process is achieved through the expansion and contraction of the dartos muscle, which causes the scrotal skin to wrinkle. When the muscle contracts, the surface area available for heat loss is reduced, resulting in decreased heat loss and warmer testicles. Conversely, when the muscle expands, the surface area increases, promoting heat loss and cooling the testicles.
This regulatory mechanism is essential for maintaining the optimal temperature required for spermatogenesis, the process of sperm production. By contracting and relaxing, the dartos muscle helps to elevate or lower the testes, ensuring they remain at the ideal temperature for sperm development. This function is particularly important in maintaining sperm health and fertility in males.
The dartos muscle works in conjunction with the cremaster muscle to elevate the testis. However, it is important to distinguish the function of the dartos muscle from the cremasteric reflex, which involves the cremaster muscle specifically. The cremaster muscle is somatically innervated, while the dartos muscle is sympathetically innervated within the scrotum.
In summary, the dartos muscle's ability to regulate testicle temperature through expansion and contraction is vital for promoting spermatogenesis and maintaining male fertility. Its role in temperature regulation ensures that the testicles remain within the optimal temperature range for healthy sperm production.
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The dartos muscle is sympathetically innervated
The dartos muscle is a sympathetically innervated dermal muscle layer within the scrotum. It is distinct from the somatically innervated cremasteric muscle. The dartos muscle did not contract in response to carbachol, nicotine, histamine, 5-hydroxytryptamine, or substance P. However, contractile responses to field stimulation and noradrenaline were much greater at 30°C compared to 40°C. The rat dartos muscle receives a functional sympathetic innervation and contracts to noradrenaline via α-adrenoceptors.
The dartos muscle is the thin rugated fascial muscle of the scrotum made of smooth muscle. It forms from the subcutaneous tissue of the scrotum and base of the penis and attaches to the scrotal skin and fibrous midline septum between the testes. The scrotum consists of a skin pouch overlying various fibroelastic and muscular layers, of which the most prominent is the tunica dartos. The dartos layers are confluent between the testes, where they form the intertesticular septum.
The human tunica dartos has been investigated by light, fluorescence, and electron microscopy. It consists of solid bundles of smooth musculature in the subcutis and small bundles or single muscle cells in the corium. Smooth muscle bundles in both the subcutis and corium are composed of ordinary smooth muscle cells. 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 reflex (DR) is a sympathetically mediated scrotal reflex. The DR test can be used to assess scrotal autonomic innervation and evaluate the thoracolumbar sympathetic and genitofemoral nerve pathways. Abnormalities of dartos innervation may impact testis thermoregulation and spermatogenesis.
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The dartos fascia keeps the foreskin close to the penis
The dartos fascia is a thin rugated fascial muscle that forms from the subcutaneous tissue of the scrotum and base of the penis. It attaches to the scrotal skin and the fibrous midline septum between the testes. The dartos muscle is the scrotal part of the dartos fascia and is composed of smooth muscle cells.
In the penis, the dartos fascia has a loose attachment to Buck's fascia, allowing for a high degree of mobility of the penile skin over the underlying tissue. This loose attachment also carries the blood supply of the penile skin through a network of vessels that arise from the external pudendal vessels.
The dartos fascia plays a crucial role in maintaining the proximity of the foreskin to the glans penis throughout life. In infancy, the dartos fascia functions as a one-way check valve at the tip of the foreskin, allowing urine to pass out while preventing the entry of foreign matter and pathogens. As maturity increases, there is a corresponding increase in elastic fibres, enabling the foreskin to become retractable by adulthood and move freely back and forth.
The dartos fascia's ability to keep the foreskin close to the penis is essential for maintaining urinary and reproductive health in males. Its smooth muscle composition allows for the necessary flexibility and mobility of the penile skin, ensuring comfort and proper functioning of the male reproductive system.
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Frequently asked questions
The dartos muscle is a sympathetically innervated dermal layer within the scrotum, distinct from the somatically innervated cremaster muscle.
The dartos muscle regulates the temperature of the testicles, which promotes spermatogenesis. It does this by expanding or contracting to wrinkle the scrotal skin.
The dartos fascia is the scrotal part of the dartos muscle, composed of smooth cells. It is also responsible for carrying the blood supply of the penile skin.
The dartos fascia keeps the foreskin close to the glans penis throughout life. In infancy, it operates as a one-way check valve at the tip of the foreskin, allowing urine to pass out and prohibiting the entry of foreign matter and pathogens.
