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Body of ilium

The body of the ilium is the thick, inferior part of the ilium, forming the lower portion of the hip bone. It contributes significantly to the formation of the acetabulum, where it unites with the bodies of the ischium and pubis. The body provides major articular and muscular surfaces essential for hip stability and locomotion.

Superiorly, the body transitions into the ala of the ilium (wing of the ilium). Inferiorly, it helps form the acetabular fossa and lunate surface, which articulate with the femoral head. The medial surface contributes to the iliac fossa and pelvic cavity, while the lateral surface gives attachment to several gluteal muscles.

The body of the ilium is crucial in load transmission from the axial skeleton to the lower limbs and serves as an anchor point for many muscles of the hip and thigh, as well as ligaments stabilizing the pelvis.

Attachments

  • Muscles:

    • Iliacus (medial surface)

    • Rectus femoris (anterior inferior iliac spine, part of ilium body)

    • Obturator internus (near acetabulum)

    • Portions of gluteal muscles attach to lateral aspect near acetabulum

  • Ligaments:

    • Capsular ligaments of the hip joint attach to the acetabular margin formed partly by the ilium

Synonyms

  • Iliac body

  • Corpus ossis ilii

  • Inferior ilium

Function

  • Forms part of the acetabulum, stabilizing the hip joint

  • Provides attachment points for hip flexors, extensors, and stabilizers

  • Transmits weight from spine to lower limbs

  • Contributes to the bony framework of the pelvic cavity

Nerve Supply (related muscles)

  • Iliacus: femoral nerve (L2–L4)

  • Rectus femoris: femoral nerve (L2–L4)

  • Obturator internus: nerve to obturator internus (L5–S2)

Arterial Supply

  • Iliolumbar artery (branch of internal iliac artery)

  • Obturator artery (branch of internal iliac)

  • Superior gluteal artery (branch of internal iliac)

  • Femoral artery branches (via circumflex arteries)

Venous Drainage

  • Iliolumbar vein, obturator vein, and gluteal veins → internal iliac vein

  • Collateral drainage via femoral vein tributaries

MRI Appearance

T1-weighted images:

  • Bone cortex: hypointense (dark rim)

  • Marrow: intermediate signal depending on fat content

  • Useful for detecting marrow infiltration, fractures, or cortical outline

T2-weighted images:

  • Cortex: hypointense

  • Marrow: intermediate to hyperintense in younger patients (higher water content), more intermediate in adults (fatty marrow)

  • Detects bone edema, cysts, and cartilage interface at acetabulum

PD Fat-Saturated (Proton Density FS):

  • Cortex: remains dark

  • Marrow edema or stress reaction: bright hyperintense signal

  • Excellent for evaluating stress fractures, osteitis, or sacroiliac inflammation extending into ilium body

STIR:

  • Cortex: dark

  • Marrow edema, trauma, infection, or inflammation: hyperintense signal

  • Sensitive for acute injuries and inflammatory pathology

T1 Post-Gadolinium (with fat saturation):

  • Normal bone marrow: mild enhancement

  • Pathologic marrow infiltration (tumor, infection): heterogeneous or strong enhancement

  • Soft tissue enhancement around ilium helps detect abscesses or neoplastic invasion

3D T2-weighted Imaging:

  • Provides detailed multiplanar reconstructions of acetabular contribution of ilium

  • Highlights cortical integrity and relationship to acetabulum

  • Useful in arthroplasty and pelvic osteotomy planning

CT Appearance

Non-contrast CT:

  • Cortex: sharply hyperdense outline

  • Marrow: lower density compared to cortex

  • Excellent for fracture detection, cortical bone assessment, dysplasia, or acetabular morphology

CT Post-Contrast:

  • Bone: unchanged

  • Soft tissue lesions, tumors, or inflammation adjacent to ilium show enhancement

  • Useful for oncologic evaluation and surgical planning

CT VRT 3D image

Body of ilium 3 ct image

CT image

Body of ilium CT axial image

MRI image

Body of ilium MRI axial anatomy image-img-00000-00000

MRI image

Body of ilium MRI axial anatomy image-img-00000-00000_00001