Ischiocavernosus
Pelvis & Perineum · Trunk
The ischiocavernosus is a paired muscle of the superficial perineal pouch that overlies the crus of the erectile body. It arises from the ischial tuberosity and the adjacent ischiopubic ramus and runs forward and medially to insert onto the crus of the penis in males or the crus of the clitoris in females. By compressing the crus, it impedes venous return from the erectile tissue and so helps to maintain erection of the penis or clitoris. It is supplied by the perineal branch of the pudendal nerve (S2-S4).
Origin, Insertion, Action & Nerve
Origin
Ischial tuberosity and ischiopubic ramus
Insertion
Crus of the penis (males); crus of the clitoris (females)
Action
Compresses the crus to maintain erection of the penis or clitoris
Nerve
Perineal branch of the pudendal nerve (S2–S4)
Attachments explained
The Ischiocavernosus is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.
Origin
Ischial tuberosity and ischiopubic ramus
Insertion
Crus of the penis (males); crus of the clitoris (females)
Action & function
When the Ischiocavernosus contracts, it produces the following movement: Compresses the crus to maintain erection of the penis or clitoris.
As part of the Pelvis & Perineum group of the Trunk, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.
Nerve supply & clinical relevance
The Ischiocavernosus receives its nerve supply from the Perineal branch of the pudendal nerve (S2–S4). This nerve carries fibres from spinal segment(s) S2, S4.
Because a muscle can only contract when its nerve is intact, injury to the Perineal branch of the pudendal nerve or to its spinal roots (S2, S4) can weaken or paralyse the Ischiocavernosus, impairing the movements it normally produces (compresses the crus to maintain erection of the penis or clitoris). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Ischiocavernosus (the OIANS method)
Read the name as a map: ischio for its origin on the ischium and cavernosus for its insertion on the crus of the corpus cavernosum. Because it wraps the crus, its single job of maintaining erection by compressing that erectile tissue follows directly, and the muscle need not be learned as anything more complicated than a crus-squeezing strap.
Contrast it with bulbospongiosus to lock in the pair: ischiocavernosus works on the crus while bulbospongiosus works on the bulb, and both share the perineal branch of the pudendal nerve (S2-S4). Holding the two side by side, one for the crus and one for the bulb, prevents the common mix-up among the superficial perineal muscles.
Frequently asked questions
Where is the Ischiocavernosus located?
The Ischiocavernosus is a muscle of the Pelvis & Perineum group, located in the Trunk.
What is the origin of the Ischiocavernosus?
Ischial tuberosity and ischiopubic ramus
What is the insertion of the Ischiocavernosus?
Crus of the penis (males); crus of the clitoris (females)
What movements does the Ischiocavernosus produce?
Compresses the crus to maintain erection of the penis or clitoris
What nerve supplies the Ischiocavernosus?
Perineal branch of the pudendal nerve (S2–S4)
Is the Ischiocavernosus free to study in OIANS?
The Ischiocavernosus is always free to browse. Its full origin, insertion, action and nerve details are open to everyone in the Muscle Directory. Quiz and Flashcard practice for the Trunk is part of the one-time Lifetime upgrade, though; only the Upper Limb decks are free to test yourself on.
Related muscles
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