Musculus pubococcygeus – Anatomy and Function

What is the Musculus pubococcygeus?

The musculus pubococcygeus (abbreviated M. pubococcygeus, or pubococcygeal muscle) is a paired, flat skeletal muscle that forms part of the musculus levator ani – the most important muscle complex of the pelvic floor. It runs on each side from the pubic bone (os pubis) to the coccyx (os coccygis), which is reflected in its name: pubis (pubic bone) and coccygeus (coccyx).

Together with the musculus iliococcygeus and musculus puborectalis, it forms the musculotendinous plate of the pelvic floor, which supports the pelvic organs from below. Depending on the orientation of the muscle fibers, different portions of the M. pubococcygeus can be distinguished: the musculus pubovaginalis (in females), the musculus puboprostaticus (in males), and the musculus puboanalis.

Anatomy and Location

The M. pubococcygeus originates from the posterior surface of the pubic bone and the obturator fascia (the connective tissue layer of the obturator muscle). From there, the muscle fibers run posteriorly and inferiorly toward the coccyx and the anococcygeal ligament, a fibrous band between the anus and the coccyx.

Along its course, the muscle surrounds important structures:

• In females: the urethra, vagina and rectum
• In males: the urethra, prostate and rectum

Innervation is primarily provided by the pudendal nerve and direct branches of the sacral plexus (S3–S4).

Functions of the Musculus pubococcygeus

The M. pubococcygeus performs several essential functions in the body:

• Support of pelvic organs: It forms a musculotendinous base that keeps the bladder, uterus, vagina and rectum in their proper positions.
• Continence function: Its tension around the urethra and rectum contributes to bladder and bowel control, preventing involuntary loss of urine or stool.
• Sexual function: In females, the M. pubovaginalis portion surrounds the vagina and plays a role in sexual sensation and the ability to achieve orgasm. In males, it is involved in erection and ejaculation.
• Pelvic stabilization: Together with the other pelvic floor muscles, it stabilizes the pelvis during physical exertion such as lifting, coughing or sneezing.
• Birth canal: During childbirth, the elasticity of the muscle allows the passage of the baby through the birth canal.

Clinical Significance

Pelvic Floor Weakness

Weakness of the M. pubococcygeus can lead to various complaints. The most common clinical problems include:

• Stress urinary incontinence: Involuntary loss of urine during physical activity such as coughing, sneezing or exercise
• Pelvic organ prolapse: Descent of the bladder (cystocele), uterus or rectum (rectocele) due to insufficient musculotendinous support
• Sexual dysfunction: Pain during intercourse (dyspareunia) or reduced sexual sensation

Vaginismus and Hypertonia

An excessively tense M. pubococcygeus can lead to vaginismus – an involuntary spasm of the vaginal muscles that makes sexual intercourse or gynecological examinations painful or impossible. Chronic pelvic pain can also be associated with pelvic floor hypertonia.

Postpartum Changes

After a vaginal birth, the M. pubococcygeus may be overstretched or injured, increasing the risk of incontinence and pelvic organ prolapse. Targeted pelvic floor rehabilitation after delivery is therefore medically recommended.

Diagnosis

The function of the M. pubococcygeus can be assessed using various methods:

• Clinical examination: Palpation of the muscle by a physician or therapist vaginally or rectally
• Perineal ultrasound: Ultrasound examination of the perineum to visualize the pelvic floor muscles
• Pelvic MRI: Magnetic resonance imaging for detailed anatomical assessment in cases of prolapse or injury
• Electromyography (EMG): Measurement of electrical muscle activity to assess neuromuscular function

Treatment and Training

Pelvic Floor Exercises (Kegel Exercises)

Targeted training of the M. pubococcygeus is the most important conservative measure for pelvic floor weakness. So-called Kegel exercises (named after gynecologist Arnold Kegel) consist of consciously contracting and relaxing the pelvic floor muscles and can significantly improve incontinence and prolapse symptoms.

Physiotherapy

Specialized pelvic floor physiotherapists use not only exercises but also biofeedback, electrical stimulation and manual techniques to specifically strengthen the muscle or relieve hypertonia.

Surgical Treatment

In cases of severe pelvic organ prolapse or treatment-resistant incontinence, surgical procedures may be necessary, such as the insertion of support slings or reconstructive pelvic floor surgery.

References

1. Schiebler, T.H. & Korf, H.W. (2007). Anatomie – Histologie, Entwicklungsgeschichte, makroskopische und mikroskopische Anatomie, Topographie. Steinkopff Verlag.
2. Ashton-Miller, J.A. & DeLancey, J.O.L. (2007). Functional anatomy of the female pelvic floor. Annals of the New York Academy of Sciences, 1101, 266–296.
3. Bø, K. et al. (2015). Evidence-Based Physical Therapy for the Pelvic Floor. Elsevier Churchill Livingstone.