Ischiocavernosus is a bilateral, perineal muscle located in the superficial perineal space of the urogenital triangle. It is a part of the superficial group of perineal muscles, together with bulbospongiosus and superficial transverse perineal muscles.
This muscle extends between the ischium of the hip bone and the crura of the penis or of the clitoris in males and females, respectively. Contraction of ischiocavernosus due to nervous inputs from the pudendal nerve helps to maintain penile/clitoral erections during sexual arousal and intercourse.
|Origin||Ischial tuberosity and ramus|
|Insertion||Crus of clitoris or penis|
|Action||Pushes blood from root of clitoris/penis to body i.e. maintains erection of penis/clitoris|
|Innervation||Deep branch of perineal nerve (of pudendal nerve) (S2-S4)|
|Blood supply||Perineal artery|
This article will describe the anatomy and functions of the ischiocavernosus muscle.
Origin and insertion
Ischiocavernosus originates from the medial aspect of the ischial tuberosity and ischial ramus of the hip bone. The muscle fibers travel in an anterior direction along the medial aspect of the ischial ramus towards the crura of the penis and clitoris. Here, the ischiocavernosus surrounds these structures, inserting into their lateral and inferior surfaces.
Ischiocavernosus is closely related to the other two superficial perineal muscles within the urogenital triangle of perineum; bulbospongiosus and superficial transverse perineal muscle. Together, these muscles comprise a triangular space filled with adipose tissue. In both sexes, ischiocavernosus is located anterior to the attachments of the superficial transverse perineal muscle. In addition, ischiocavernosus travels laterally to the bulbospongiosus, with the perineal artery and nerve coursing between them.
All superficial perineal muscles, including ischiocavernosus, lie superficial to the perineal membrane. They are separated from the perineal membrane by the subcutaneous perineal space. In turn, the superficial perineal muscles are covered superficially by the deep perineal fascia (of Gallaudet).
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The arterial blood supply to the ischiocavernosus muscle is provided by the perineal artery, a branch of the internal pudendal artery. The latter stems from the internal iliac artery.
Contraction of the ischiocavernosus muscle compresses the crura of the penis/clitoris, pushing the blood away from their roots into the distal parts. The surrounding veins which drain the penis/clitoris are also compressed by ischiocavernosus, restricting venous outflow. This increased pool of venous blood maintains the turgidity (distension) of the penis/clitoris, helping to maintain an erection during sexual arousal and intercourse. In males, ischiocavernosus also acts together to stabilize the penis when fully erect.