Perineal artery

The perineal artery is a branch of the internal pudendal artery that supplies blood to the perineum, which includes the skin and muscles around the external genitalia and the anal region.

Location

The perineal artery arises from the internal pudendal artery within the pelvis. It exits the pelvis through the greater sciatic foramen and then re-enters through the lesser sciatic foramen, traveling within the ischioanal fossa. The artery runs anteriorly along the perineum, deep to the superficial fascia, and it supplies the muscles and skin of the perineal region, including the ischiocavernosus and bulbospongiosus muscles. It also contributes to the vascularization of the scrotum in males and the labia majora in females. The artery eventually anastomoses with other branches of the internal pudendal artery.

Structure and Anatomy

Origin

The perineal artery originates from the internal pudendal artery, which is itself a branch of the internal iliac artery. The internal pudendal artery provides blood to the perineum and external genitalia, and the perineal artery is one of its terminal branches. It typically arises after the internal pudendal artery exits the pelvis and enters the perineal region through the lesser sciatic foramen.

Course

The perineal artery begins its course by following the internal pudendal artery as it exits the greater sciatic foramen and re-enters the pelvis through the lesser sciatic foramen. From here, it travels in the ischioanal fossa, a fat-filled space located on either side of the anal canal, which provides a passage for neurovascular structures in the perineal region.

The artery runs anteriorly within the superficial perineal space, lying deep to the superficial fascia but superficial to the perineal muscles. It travels anteriorly to supply the muscles and tissues of the urogenital triangle and perineal body.

Branches

As the perineal artery courses through the perineal region, it gives off several branches that supply various structures in the area:

• Muscular Branches: These small branches supply the ischiocavernosus, bulbospongiosus, and superficial transverse perineal muscles, which are involved in maintaining the structure and function of the perineum, especially during micturition, ejaculation, and supporting pelvic structures.
• Posterior Scrotal/Labial Arteries: These branches are responsible for supplying the external genitalia. In males, they form the posterior scrotal arteries, which supply blood to the scrotum and skin of the perineum. In females, the equivalent branches are the posterior labial arteries, which supply the labia majora and surrounding tissues.

Termination

The perineal artery terminates by anastomosing with other arteries in the perineal region. These include branches of the internal pudendal artery, such as the inferior rectal artery and the deep artery of the penis (in males) or deep artery of the clitoris (in females). The network of these arteries ensures a comprehensive blood supply to the perineum and external genitalia.

Anatomical Relations

• Internal Pudendal Artery: The perineal artery is a branch of the internal pudendal artery, which is the main vessel supplying the perineum and external genitalia. The internal pudendal artery travels through the pudendal canal (Alcock’s canal) alongside the pudendal nerve and vein.
• Ischioanal Fossa: The perineal artery passes through the ischioanal fossa, a space located between the ischium and the rectum. This space contains fat, neurovascular structures, and the pudendal vessels and nerve. The artery travels through this fossa as it courses anteriorly to reach the perineum.
• Superficial Perineal Space: The artery runs in the superficial perineal space, a region between the perineal membrane (part of the pelvic floor) and the skin. In this space, the perineal artery supplies the perineal muscles and tissues, including the bulbospongiosus and ischiocavernosus muscles.
• External Genitalia: In males, the artery contributes to the blood supply of the scrotum and surrounding structures through its posterior scrotal branches. In females, it supplies the labia majora and nearby skin through the posterior labial arteries.

Anastomoses

The perineal artery forms anastomoses with other branches of the internal pudendal artery, such as:

• Inferior Rectal Artery: This artery supplies the lower part of the rectum and anal canal, and it shares anastomoses with the perineal artery to ensure a robust blood supply to the perineum and the anal region.
• Deep Artery of the Penis/Clitoris: In males, the deep artery of the penis helps supply blood to the erectile tissues of the penis, and in females, the deep artery of the clitoris supplies blood to the clitoris. These anastomoses support the vascular network necessary for the external genitalia and perineal structures.

Gender-Specific Anatomy

• Males: In males, the perineal artery gives off the posterior scrotal arteries, which supply the scrotum and parts of the perineum. These arteries provide blood to the skin, fascia, and muscle layers of the scrotum, contributing to the overall blood supply of the external genitalia.
• Females: In females, the equivalent branches of the perineal artery are the posterior labial arteries, which supply the labia majora and the perineal skin. These arteries provide oxygenated blood to the tissues surrounding the external genitalia, ensuring proper tissue health and function.

Relationships with Other Structures

• Pudendal Nerve: The perineal artery runs alongside the pudendal nerve, which is the primary nerve supplying motor and sensory innervation to the perineal region. The pudendal nerve travels with the artery through the pudendal canal and gives off branches that innervate the muscles of the perineum, such as the bulbospongiosus and ischiocavernosus muscles.
• Ischiocavernosus and Bulbospongiosus Muscles: The perineal artery supplies the ischiocavernosus and bulbospongiosus muscles, which play important roles in sexual function and the support of the pelvic floor. These muscles are involved in the compression of erectile tissues during sexual activity and assist in the support of the pelvic organs.

Surface Anatomy

The perineal artery is located deep within the perineal region, beneath the superficial fascia. Its branches, such as the posterior scrotal or labial arteries, supply the skin and soft tissues, making them more accessible during surgical procedures on the perineum or genital region. While not palpable, the artery’s proximity to important perineal structures is significant in clinical procedures.

Function

Blood Supply to the Perineal Muscles

The perineal artery plays a crucial role in providing oxygenated blood to the perineal muscles, including the ischiocavernosus, bulbospongiosus, and superficial transverse perineal muscles. These muscles are essential for various functions, including supporting the pelvic floor, maintaining genital integrity, and assisting in sexual functions. For example, the ischiocavernosus helps maintain penile or clitoral erection by compressing the outflow veins, while the bulbospongiosus assists in the expulsion of semen in males and contributes to the contraction of the vaginal opening in females. By ensuring a steady blood supply, the perineal artery supports the proper functioning of these muscles during physical and sexual activities.

Blood Supply to the External Genitalia

The perineal artery, through its posterior scrotal arteries (in males) or posterior labial arteries (in females), provides blood to the external genitalia.

• In males, the posterior scrotal arteries supply blood to the scrotum, ensuring that the skin, connective tissues, and underlying structures of the scrotum receive adequate blood for their normal function and temperature regulation. The scrotal blood supply is crucial for maintaining the optimal environment for the testes, which is necessary for proper spermatogenesis.
• In females, the posterior labial arteries supply blood to the labia majora and the surrounding tissues of the external genitalia. Adequate vascularization supports the function of these tissues during reproductive activities, as well as maintaining tissue health and providing the blood necessary for wound healing after injuries or childbirth.

Contribution to the Vascularization of the Perineal Region

The perineal artery is part of the broader vascular network that supplies the perineum, an area that includes the genitalia, anal region, and the supporting structures of the pelvic floor. By contributing to the blood supply of the perineal region, the perineal artery supports the maintenance of tissue health, healing after injury, and the overall function of the perineal structures. This region is involved in both reproductive and excretory functions, making an uninterrupted blood supply essential for its proper function.

Support for Sexual Function

The perineal artery indirectly supports sexual function in both males and females by supplying the muscles and skin of the external genitalia. The ischiocavernosus and bulbospongiosus muscles, which are supplied by the perineal artery, are essential in males for the compression of the penile crura during erection and ejaculation, helping to maintain the rigidity of the penis. In females, these muscles contract to aid in the compression of the vaginal opening and enhance sexual response. Without adequate blood flow from the perineal artery, the function of these muscles could be impaired, leading to difficulties in achieving or maintaining erections or other sexual dysfunctions.

Blood Supply to the Perineal Body

The perineal artery also supplies blood to the perineal body, a central fibromuscular structure located between the anus and the genitalia. The perineal body is critical for maintaining the integrity of the pelvic floor and provides attachment points for several perineal muscles, including the bulbospongiosus and transverse perineal muscles. By delivering oxygen and nutrients to the perineal body, the perineal artery helps maintain the structure and strength of this important pelvic support system.

Contribution to the Anal Region

Though the primary supply to the anal region comes from the inferior rectal artery (another branch of the internal pudendal artery), the perineal artery contributes to the vascularization of the perianal area, including parts of the anal sphincter and surrounding tissues. The arterial supply ensures that these tissues remain viable and capable of functioning effectively during defecation and maintaining continence.

Role in Wound Healing and Tissue Repair

The posterior scrotal and posterior labial arteries, branches of the perineal artery, play a key role in supporting wound healing and tissue repair in the perineum and external genitalia. After injury, trauma, or surgical procedures such as episiotomies (in females) or scrotal surgeries (in males), the blood supply from the perineal artery ensures that the tissues receive the oxygen and nutrients needed for repair and regeneration. Adequate vascularization from the perineal artery is crucial for reducing the risk of complications, such as infection or delayed healing.

Anastomosis and Collateral Circulation

The perineal artery contributes to the formation of anastomoses with other arteries in the pelvic region, such as the inferior rectal artery, deep artery of the penis (in males), or deep artery of the clitoris (in females). This network of blood vessels helps ensure that the perineal and genital regions receive a continuous blood supply even if one artery becomes compromised. These anastomoses provide collateral circulation, which is particularly important during periods of increased blood flow demand, such as during sexual arousal or after injury.

Nutrient Delivery and Metabolic Support

Like all arteries, the perineal artery is responsible for delivering oxygenated blood and essential nutrients to the tissues it supplies. The perineal region includes muscles, skin, connective tissues, and external genitalia that require a constant supply of nutrients to maintain their structural integrity and function. The artery supports cellular respiration, tissue metabolism, and the production of energy for muscle contraction, allowing for proper functioning during activities such as sexual intercourse, childbirth, and defecation.

Removal of Metabolic Waste Products

The perineal artery, through its continuous blood flow, helps in the removal of metabolic waste products, such as carbon dioxide and lactic acid, from the muscles and tissues of the perineum. This process is essential for preventing muscle fatigue and maintaining tissue health, particularly during times of physical exertion or sustained contraction, such as during childbirth or prolonged periods of sitting. By maintaining efficient waste removal, the perineal artery ensures that tissues remain healthy and capable of performing their functions without damage or fatigue.

Clinical Significance

The perineal artery plays a vital role in supplying blood to the perineum, including the external genitalia, perineal muscles, and anal region. Its clinical significance is particularly relevant in surgeries involving the perineum and genital region, such as episiotomies during childbirth, perineal tears, or reconstructive surgeries for genital injuries. Damage to the perineal artery can lead to bleeding complications, impaired healing, and tissue ischemia, potentially affecting sexual function and pelvic support.

In males, branches of the perineal artery, such as the posterior scrotal arteries, supply the scrotum, while in females, the posterior labial arteries supply the labia majora. Disruption to this blood flow can lead to issues with tissue viability, delayed healing, or scarring after injuries or surgeries. Furthermore, the artery’s role in providing collateral circulation ensures continuous blood flow to the perineum, which is essential for maintaining the health and function of the muscles and tissues in this region.