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Pubococcygeus muscle

The pubococcygeus is a major component of the levator ani group of pelvic floor muscles, along with the puborectalis and iliococcygeus. It stretches from the pubic bone to the coccyx, forming a supportive sling for pelvic organs. The muscle plays a critical role in urinary and fecal continence, sexual function, and support of abdominal and pelvic viscera. Weakness, trauma, or injury to the pubococcygeus is associated with prolapse, incontinence, and pelvic floor dysfunction.

Synonyms

  • Pubococcygeal muscle

  • Central component of levator ani

  • Kegel muscle (clinical term)

Origin, Course, and Insertion

  • Origin: Arises from the posterior surface of the pubic body and the anterior part of the tendinous arch of the levator ani

  • Course: Fibers run posteriorly and medially, forming part of the muscular pelvic diaphragm; they pass around the pelvic viscera and interdigitate with fibers of the opposite side

  • Insertion: Attaches into the anococcygeal raphe and coccyx; some fibers insert into the perineal body and walls of pelvic viscera (prostate, vagina, urethra, rectum)

Relations

  • Anteriorly: Pubic symphysis and urogenital hiatus

  • Posteriorly: Coccyx and anococcygeal raphe

  • Superiorly: Pelvic viscera (bladder, uterus, rectum)

  • Inferiorly: Perineal body and superficial perineal structures

Function

  • Supports pelvic viscera (bladder, rectum, uterus in females, prostate in males)

  • Maintains urinary and fecal continence

  • Assists in control of intra-abdominal pressure

  • Plays a role in sexual function (tightening vaginal or anal canal during contraction)

  • Contracts during coughing, sneezing, and physical exertion to protect pelvic organs

Clinical Significance

  • Injury or weakness contributes to urinary incontinence, fecal incontinence, and pelvic organ prolapse

  • Targeted in Kegel exercises for pelvic floor strengthening

  • Commonly affected in obstetric trauma, pelvic surgery, or neuropathy

  • Important landmark in pelvic MRI for evaluation of pelvic floor dysfunction and descent

MRI Appearance

T1-weighted images:

  • Normal muscle appears as low-to-intermediate signal intensity

  • Fat appears bright, outlining the muscle borders

  • No fluid: Pouch-like spaces are collapsed, showing only muscle and fat planes

T2-weighted images:

  • Muscle demonstrates low signal intensity

  • Fat shows intermediate-to-bright signal, providing contrast

  • Fluid (if present): bright signal between pelvic organs and muscle

STIR (Short Tau Inversion Recovery):

  • Normal muscle shows low signal intensity

  • Fat is suppressed and appears dark

  • Pathology (edema, tear, inflammation) appears bright hyperintense

T1 Fat-Sat Post-Contrast:

  • Normal muscle shows mild homogeneous enhancement

  • Fat suppressed and appears dark

  • Pathology (myositis, neoplasm, abscess) demonstrates focal or rim enhancement

CT Appearance

Non-Contrast CT:

  • Muscle appears as soft tissue density in the pelvic floor

  • Fat appears as low density surrounding the muscle

  • No fluid: pouch-like recesses not visible unless pathology is present

Post-Contrast CT:

  • Muscle enhances mildly and homogeneously

  • Inflammation or tumors enhance heterogeneously

  • Abscess appears as a low-attenuation center with rim enhancement

MRI images

Pubococcygeus muscle MRI axial anatomy image-img-00000-00000

CT image

Pubococcygeus muscle CT axial anatomy image-img-00000-00000