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Pubic bone

The pubic bone (pubis) is the anterior and inferior portion of the hip bone (os coxae), contributing to the formation of the acetabulum and the pelvis. It consists of three main parts: the body, the superior pubic ramus, and the inferior pubic ramus. The two pubic bones meet in the midline at the symphysis pubis, a fibrocartilaginous joint.

  • The body forms the medial portion adjacent to the symphysis pubis.

  • The superior ramus extends laterally to contribute to the acetabulum.

  • The inferior ramus extends posterolaterally, joining the ischium.

The pubic bone provides attachment for multiple muscles (adductors, gracilis, rectus abdominis, pyramidalis) and ligaments (inguinal ligament, pubofemoral ligament). It is also a major landmark in pelvic surgery and radiology.

Clinically, the pubic bone is important in pelvic fractures, osteitis pubis, symphysis pubis dysfunction (SPD) in pregnancy, hernias, and tumors.

Synonyms

  • Pubis

  • Os pubis

  • Pubic portion of hip bone

Function

  • Contributes to the acetabulum, forming part of the hip joint

  • Provides attachment for muscles of the abdomen, pelvis, and thigh

  • Transmits weight and forces across the pelvis via the pubic symphysis

  • Serves as a landmark in surgical approaches to the pelvis and lower abdomen

Nerve Supply (related structures)

  • Muscles attached (adductor group, gracilis) supplied by the obturator nerve (L2–L4)

  • Rectus abdominis/pyramidalis attachment: innervated by thoracoabdominal nerves (T7–T12)

  • Sensory innervation of the region: branches of ilioinguinal and genitofemoral nerves

Arterial Supply

  • Obturator artery (branch of internal iliac artery)

  • Inferior epigastric artery (via pubic branch)

  • External pudendal artery (branch of femoral artery)

  • Anastomoses form an important collateral circulation near the symphysis

Venous Drainage

  • Obturator vein → internal iliac vein

  • Inferior epigastric vein → external iliac vein

  • External pudendal vein → femoral vein

MRI Appearance

T1-weighted images:

  • Bone cortex: uniformly hypointense (dark)

  • Marrow: intermediate signal due to fatty content

  • Pubic symphysis fibrocartilage: hypointense band

T2-weighted images:

  • Cortex: remains hypointense

  • Marrow: variable, often intermediate-to-bright if edema or infiltration present

  • Symphysis fibrocartilage: intermediate-to-low signal

  • Detects early osteitis pubis, edema, or fractures

PD Fat-Saturated (Proton Density FS):

  • Cortex: hypointense

  • Marrow edema or stress injury: hyperintense

  • Highly sensitive for osteitis pubis, stress fractures, and athletic pubalgia

STIR:

  • Cortex: hypointense

  • Marrow and peripubic edema: hyperintense, fat suppressed

  • Excellent for detecting acute trauma, inflammation, or infection

T1 Post-Gadolinium (with fat saturation):

  • Bone cortex: no enhancement

  • Marrow: mild enhancement normally

  • Pathology: osteitis pubis, tumors, or infections show strong heterogeneous enhancement

  • Defines abscesses or tumor infiltration into marrow and soft tissues

3D T2-weighted Imaging:

  • Bone cortex: hypointense rim with smooth contour

  • Marrow: intermediate

  • Provides multiplanar 3D reconstructions to evaluate pubic symphysis, rami fractures, and pelvic morphology

CT Appearance

Non-contrast CT:

  • Cortex: hyperdense and sharply defined

  • Marrow cavity: hypodense relative to cortex

  • Best for fractures, cortical irregularities, degenerative changes, and dysplasia

CT Post-Contrast:

  • Bone cortex: unchanged

  • Soft tissues: enhancement highlights inflammation, tumors, or infection

  • Useful for detecting abscess, neoplastic invasion, or vascular abnormalities near pubis

Clinical Significance

  • Fractures: common in pelvic trauma, particularly in elderly (osteoporotic) patients.

  • Osteitis pubis: inflammatory condition seen in athletes and post-surgery.

  • Symphysis pubis dysfunction (SPD): associated with pregnancy and pelvic instability.

  • Tumors and metastases: primary pelvic tumors or metastatic lesions often involve pubic bone.

  • Hernia evaluation: pubic bone is a landmark for inguinal and femoral hernia imaging.

CT VRT 3D image

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CT image

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MRI image

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