Ischiocavernosus

What is the Ischiocavernosus

The ischiocavernosus is a small paired skeletal muscle in the human perineum. It is one of the three muscles in the superficial perineal pouch, with the other two being the superficial transverse perineal and the bulbospongiosus.

The muscle supports movements and functions associated with sexual activity, including helping to maintain the erection of the penis or clitoris by compressing erectile tissue.

Although its general structure and function are similar in both sexes, there are slight differences in its formation and attachments. In older anatomical texts, the male and female ischiocavernosus muscles were referred to as the erector penis and erector clitoridis, respectively. However, these terms are now considered outdated and are not used in modern anatomical nomenclature.

Anatomy

The small thin muscle has a common origin in both males and females, though the insertion differs.

Location and Attachments

Origin	The ischial tuberosity and ramus
Insertion	In males: The crus of the penisIn females: The crus of the clitoris

Origin

It originates from the inner surface of the ischial tuberosity and the ramus of the ischium on both sides, via tendinous and muscular slips. Some fibers may also arise from the inferior surface of the pubic rami.

Insertion

From their origin, the muscle fibers run medially along the ischial rami toward the front of the pelvis. In males, the muscle inserts into the sides of the crura at the base of the penis. In females, it inserts into the crura of the clitoris, which is the female homolog of the penis.

Relations With Surrounding Muscles and Structures

Being part of the superficial perineal pouch, the ischiocavernosus lies superficial to the perineal membrane and is covered externally by the deep perineal fascia. Together with the other components of this pouch, the bulbospongiosus, and the superficial transverse perineal muscles, it helps form the urogenital triangle at the anterior part of the perineum.

In both sexes, the ischiocavernosus is positioned anterior to the origin of the superficial transverse perineal muscle at the ischial tuberosity. Medially, it is bordered by the bulbospongiosus muscle with the perineal artery and nerve passing between them.

Function

Action

Maintaining erection of the penis (males)  or clitoris (female)

The ischiocavernosus muscle contracts in response to input from the pudendal nerve, which is the primary nerve of the pelvic floor, perineum, and genital area. Upon contraction, the muscle compresses the crura of the penis or clitoris, restricting venous drainage from the region’s primary veins, including the dorsal vein of the penis or clitoris. As a result, blood pools within the erectile tissues, making them turgid and helping to maintain erection during sexual activity.

In males, the muscle also plays an important role in stabilizing the penis during erection.

Innervation

Nerve

Perineal branch of the pudendal nerve (S2-S4)

The primary nerve supply to the muscle comes from the deep branch of the perineal nerve (deep perineal nerve), which is a terminal branch of the pudendal nerve arising from the 2nd to 4th sacral nerves (S2 to S4).

Blood Supply

Artery

Perineal artery

The muscle receives arterial supply from the perineal artery, which branches from the internal pudendal artery, itself a branch of the internal iliac artery.