Ischiocavernosus: Origin, Insertion, Nerve & Erectile Function

The Ischiocavernosus is a paired, superficial muscle of the perineum located within the urogenital triangle. It covers the crus of the penis (in males) or clitoris (in females). It plays a critical role in sexual function by maintaining erection through the compression of venous outflow.

[Image of Ischiocavernosus muscle anatomy]

Quick Anatomy Snapshot

Origin (Proximal)	Medial surface of the Ischial Tuberosity and the Ischiopubic Ramus.
Insertion (Distal)	Male: Crus of the Penis. Female: Crus of the Clitoris.
Nerve Supply	Perineal Nerve (branch of the Pudendal Nerve) - S2, S3, S4.
Blood Supply	Perineal Artery.
Primary Actions	Erection: Compresses the crus to force blood into the body of the penis/clitoris and restricts venous drainage. Stabilization: Stabilizes the erect penis or clitoris.

Deep Dive: The Pelvic Floor Stabilizer

The Ischiocavernosus is part of the superficial perineal pouch, working closely with the Bulbospongiosus and Superficial Transverse Perineal muscles.

1. Sexual Dimorphism

While present in both sexes, the muscle is larger in males.
• In Males: It embraces the crus of the penis, compressing it against the ischial bone to obstruct venous return, maintaining turgidity.
• In Females: It embraces the crus of the clitoris, performing a similar function to retard blood drainage and maintain clitoral erection.

2. The "High Pressure" Muscle

Studies show that voluntary contraction of the Ischiocavernosus can increase intracavernous pressure significantly higher than systolic blood pressure, creating the "rigid" phase of erection essential for penetration.

Physio Corner: Clinical Relevance

💪 Functional Fact: The Ischiocavernosus is one of the primary targets of Kegel Exercises (Pelvic Floor Muscle Training). Strengthening this muscle is a first-line treatment for mild to moderate Erectile Dysfunction (ED) and can help with urinary incontinence.

Palpation

This muscle is located deeply in the perineum along the bony rim of the pubic arch.
Technique: Locate the Ischial Tuberosity (sit bone). Palpate just medially and anteriorly along the bone ramus. Contraction is felt when the patient attempts to stop the flow of urine or (in males) voluntarily "lift" the penis.

⚠️ Clinical Pathology: Ischiocavernosus Reflex
This reflex involves the contraction of the Ischiocavernosus muscle in response to squeezing the glans penis or clitoris. It helps verify the integrity of the S2-S4 spinal reflex arc (Pudendal Nerve) in patients with spinal cord injury.

Assessment

Standard manual muscle testing (resistance) is not applicable. Assessment is functional.

Testing Tip: Digital rectal or vaginal examination is used to assess the tone and strength of the pelvic floor muscles as a group, rated on the Modified Oxford Scale (0-5).

Strengthening Protocols

Exercise	Description
Kegels	Voluntary contraction of the pelvic floor. Cue: "Lift the penis" or "Stop gas." Hold for 5-10 seconds.
Biofeedback	Using surface EMG or pressure probes to help the patient identify and isolate the correct muscles without using abdominals or glutes.

Frequently Asked Questions

Does it help with urination?

Indirectly. While the Bulbospongiosus is the primary "expeller" of urine (emptying the urethra), the Ischiocavernosus provides structural support to the pelvic floor, assisting in continence.

Why does it cause pain?

Hypertonicity (tightness) or trigger points in the Ischiocavernosus can cause Pudendal Neuralgia, leading to chronic pelvic pain, pain during intercourse (dyspareunia), or pain sitting on the "sit bones."

Is it a skeletal muscle?

Yes. It is a voluntary striated skeletal muscle, meaning you can consciously contract and relax it (unlike the smooth muscle of the bladder).

Test Your Knowledge: Ischiocavernosus Quiz

1. Which nerve supplies the Ischiocavernosus?

2. What is the primary function of the Ischiocavernosus?

3. Where does the Ischiocavernosus originate?

4. What structure does the Ischiocavernosus cover?

5. Which spinal levels contribute to the innervation?

6. In females, this muscle inserts onto the:

7. This muscle belongs to which anatomical triangle?

8. Is the Ischiocavernosus smooth or skeletal muscle?

9. The Ischiocavernosus helps retard the outflow of which fluid?

10. Hypertonicity in this muscle can contribute to:

References

• Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2018). Clinically Oriented Anatomy. 8th ed. Philadelphia: Wolters Kluwer.
• Standring, S. (2016). Gray's Anatomy: The Anatomical Basis of Clinical Practice. 41st ed. Elsevier.
• Newman, D. K. (2014). Pelvic Floor Exercises. Urologic Nursing.