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Superior pubic ramus

The superior pubic ramus is the upper branch of the pubic bone that extends laterally and posteriorly from the body of the pubis to join the ilium and ischium at the acetabulum. It contributes to the anterior boundary of the obturator foramen and forms part of the acetabular roof.

The superior pubic ramus is composed of compact cortical bone externally and trabecular cancellous bone internally, containing red marrow in youth and more fatty marrow in adults. Its medial end contributes to the pubic symphysis, while its lateral end blends with the iliopubic eminence before contributing to the acetabulum.

It serves as a key structural component of the pelvis, transmitting body weight from the upper body through the acetabulum to the femur. Clinically, it is important in pelvic fractures (especially pubic rami fractures), acetabular trauma, hernias, and orthopedic surgical approaches.

Attachments

  • Muscular:

    • Pectineus (from pectineal line on superior ramus)

    • Adductor longus (near pubic crest adjacent to the superior ramus)

  • Ligamentous:

    • Pectineal ligament (Cooper’s ligament)

    • Part of pubofemoral ligament (hip capsule)

  • Articulations:

    • Medially: articulates with contralateral pubic bone via pubic symphysis

    • Laterally: contributes to acetabulum

Relations

  • Forms anterior boundary of obturator canal, transmitting obturator nerve and vessels

  • Superior surface contributes to pelvic brim

  • Adjacent to bladder anteriorly and acetabulum laterally

Synonyms

  • Pubic ramus superior

  • Upper branch of pubis

  • Pars superior ossis pubis

Function

  • Structural support of the pelvic ring

  • Contributes to acetabular stability and hip articulation

  • Provides origin for pectineus and adductor muscles

  • Transmits loads across pubic symphysis and acetabulum

Nerve Supply (related structures)

  • Pectineus: femoral nerve (L2–L4), sometimes accessory obturator nerve

  • Adductor longus: obturator nerve (L2–L4)

  • Obturator nerve passes posterior-inferior to the superior pubic ramus through obturator canal

Arterial Supply

  • Obturator artery (branch of internal iliac artery)

  • Inferior epigastric artery (via pubic branch anastomosis)

  • Small contributions from medial femoral circumflex artery

Venous Drainage

  • Obturator vein → internal iliac vein

  • Anastomotic connections with inferior epigastric vein and pelvic venous plexuses

MRI Appearance

T1-weighted images:

  • Bone cortex: hypointense

  • Bone marrow: intermediate signal, higher in fatty marrow of adults

  • Excellent for detecting marrow infiltration or fracture lines

T2-weighted images:

  • Cortex: hypointense

  • Marrow: intermediate to hyperintense depending on edema or fat content

  • Useful for detecting stress fractures, cystic changes, or tumor infiltration

PD Fat-Saturated:

  • Cortex: dark hypointense

  • Marrow edema or bone stress reactions: appear hyperintense

  • Sensitive for early stress fractures and marrow pathology

STIR:

  • Cortex: hypointense

  • Marrow edema, trauma, inflammation, or infection: bright hyperintensity

  • Very sensitive for acute fracture or osteitis pubis

T1 Post-Gadolinium (with fat suppression):

  • Bone cortex: does not enhance

  • Marrow and surrounding soft tissues: enhancement in infection, tumor, or inflammation

  • Detects osteomyelitis, marrow infiltration, or soft tissue extension

3D T2-weighted Imaging:

  • Cortex: sharply hypointense

  • Marrow: intermediate

  • Excellent for multiplanar reconstructions of acetabular margin, obturator foramen, and pubic rami fractures

CT Appearance

Non-contrast CT:

  • Bone cortex: hyperdense, sharply delineated

  • Marrow: less dense compared to cortex

  • Excellent for identifying pubic rami fractures, cortical disruption, and acetabular extension

CT Post-Contrast:

  • Bone cortex: unchanged (hyperdense)

  • Soft tissues: enhance, useful for detecting hematomas, tumors, or inflammatory changes

  • Helpful in distinguishing bone lesions with soft-tissue extension

Clinical Significance

  • Pubic rami fractures: Common in elderly with osteoporosis, often low-energy injuries.

  • Acetabular fractures: Superior ramus involvement alters acetabular stability.

  • Stress fractures: Seen in athletes and military recruits; best detected on MRI (STIR/PD-FS).

  • Osteitis pubis: Inflammation around symphysis and rami, hyperintense on STIR.

  • Surgical relevance: Used as access point in hernia repairs and pelvic reconstructive surgeries.

CT VRT 3D image

Superior pubic ramus 3D CT VRT anatomy image

CT image

Superior pubic ramus ct axial image

MRI image

Superior pubic ramus MRI axial anatomy image-img-00000-00000