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Topic

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Inferior pubic ligament

The inferior pubic ligament, also known as the arcuate pubic ligament, is a strong band of connective tissue that reinforces the lower aspect of the pubic symphysis. It contributes to the stability of the anterior pelvic ring and plays a key role in resisting shear forces between the two pubic bones. Located inferior to the pubic symphysis, it blends with periosteal tissue and adjacent fascial structures, forming part of the pelvic floor support.

It is clinically significant in trauma, pregnancy-related symphyseal laxity, and in surgical planning for pelvic and urogenital procedures.

Synonyms

  • Arcuate pubic ligament

  • Subpubic ligament

  • Inferior ligament of pubic symphysis

Attachments and Course

  • Attachments:

    • Extends between the inferior rami of the pubic bones, forming a thick arch beneath the pubic symphysis

  • Course:

    • Forms a curved band running transversely beneath the pubic symphysis

    • Blends with the periosteum and fascia of adjacent muscles such as the adductor longus and gracilis origins

Relations

  • Anteriorly: Subcutaneous tissue and skin of the pubic region

  • Posteriorly: Urogenital diaphragm and pelvic floor structures

  • Superiorly: Fibrocartilaginous pubic symphysis

  • Inferiorly: Origins of the gracilis and adductor longus muscles

Nerve Supply

  • No direct innervation; associated with nearby periosteal sensory branches from the ilioinguinal nerve and pudendal nerve plexus

Arterial Supply

  • Branches from the obturator artery

  • Branches from the inferior epigastric artery

  • Contributions from the pubic branch of the external pudendal artery

Venous Drainage

  • Venous drainage into the obturator vein, inferior epigastric vein, and external pudendal vein

Function

  • Provides stability to the pubic symphysis

  • Resists shearing and tensile forces across the anterior pelvic ring

  • Contributes to the integrity of the pelvic floor

  • Important in load transfer during walking, running, and childbirth

Clinical Significance

  • Injury or laxity occurs in pelvic trauma, especially symphyseal diastasis

  • Ligament laxity is associated with pregnancy and postpartum pelvic pain

  • Can be a site of involvement in inflammatory arthropathies

  • Important landmark in pelvic surgery and imaging

MRI Appearance

T1-weighted images:

  • Appears as a low-signal band beneath the pubic symphysis

  • Fatty tissue adjacent to it appears hyperintense, helping delineation

T2-weighted images:

  • Demonstrates low signal intensity

  • Acute injury, sprain, or edema appears as bright signal within or around the ligament

STIR (Short Tau Inversion Recovery):

  • Ligament is low signal in normal state

  • Pathology or edema shows as high signal

Proton Density Fat-Sat (PD FS):

  • Normal ligament appears as a low-signal band

  • Sprain or partial tear shows focal high signal intensity

T1 Fat-Sat Post-Contrast:

  • Normal ligament shows little to no enhancement

  • Injured or inflamed ligament demonstrates focal or diffuse enhancement

CT Appearance

Non-Contrast CT:

  • Visualized as a thin, dense fibrous band beneath the pubic symphysis

  • Calcification or ossification may be seen in chronic conditions

  • Acute injury may be associated with widening of the symphyseal joint

Post-Contrast CT:

  • Minimal enhancement in normal ligament

  • Surrounding soft-tissue enhancement in cases of trauma, inflammation, or infection

  • Abscess near the pubic symphysis may show rim enhancement with central low density

MRI image

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CT image

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