Topics

Topic

design image
Body of ischium

The body of the ischium forms the posteroinferior part of the hip bone and contributes significantly to the acetabulum. It lies inferior to the ilium and posterior to the pubis, forming the strong weight-bearing portion of the pelvis. The body widens to form the ischial tuberosity, a major bony prominence that supports body weight in the seated position.

Superiorly, the body contributes to the posterior two-fifths of the acetabulum, articulating with the head of the femur. Inferiorly, it extends to form the ramus of the ischium, which joins the inferior ramus of the pubis to form the ischiopubic ramus. Posteriorly, it gives rise to the ischial spine, which separates the greater and lesser sciatic notches.

The body of the ischium serves as a site of attachment for major muscles of the hip and thigh, as well as ligaments that stabilize the pelvis. Clinically, it is important in pelvic fractures, hip joint stability, sitting balance, and surgical approaches to the pelvis and acetabulum.

Attachments

  • Ischial tuberosity (from body): origin for hamstring muscles (semimembranosus, semitendinosus, biceps femoris long head), and adductor magnus

  • Ischial spine: attachment for sacrospinous ligament and part of the pelvic diaphragm

  • Acetabular contribution: posterior portion of acetabular fossa

Synonyms

  • Corpus ossis ischii

  • Ischial body

  • Posteroinferior hip bone

Function

  • Contributes to acetabulum formation and hip joint stability

  • Provides origin for hamstring and adductor muscles

  • Bears weight during sitting via the ischial tuberosity

  • Serves as attachment for pelvic ligaments, aiding in pelvic stability

Nerve Supply (related muscles)

  • Hamstring muscles: tibial division of the sciatic nerve (L4–S3)

  • Adductor magnus (ischial origin): posterior division of obturator nerve + tibial sciatic contributions

Arterial Supply

  • Branches of the inferior gluteal artery

  • Obturator artery (acetabular contribution)

  • Perforating branches of the deep femoral artery

Venous Drainage

  • Follows arterial supply via inferior gluteal and obturator veins → internal iliac vein

MRI Appearance

T1-weighted images:

  • Bone cortex: hypointense

  • Bone marrow: intermediate signal due to fatty content

  • Clear delineation of acetabular posterior wall contribution

T2-weighted images:

  • Cortex: hypointense

  • Bone marrow: intermediate-to-bright depending on fat/water ratio

  • Pathology (edema, fracture, tumor) appears as hyperintensity

PD Fat-Saturated:

  • Cortex: dark hypointense

  • Bone marrow edema or stress fracture: bright hyperintense

  • Useful in musculoskeletal injury evaluation

STIR:

  • Suppresses fat, highlighting marrow edema, inflammation, or infiltration

  • Excellent for trauma and stress injuries

T1 Post-Gadolinium (fat-saturated):

  • Normal bone: minimal enhancement

  • Pathology (infection, tumor, inflammatory changes): abnormal enhancement of marrow and periosteum

  • Useful for distinguishing tumor infiltration vs benign marrow edema

3D T2-weighted Imaging:

  • Provides multiplanar visualization of acetabular contribution, ischial spine, and tuberosity

  • Excellent for surgical planning in pelvic fractures and acetabular reconstructions

CT Appearance

Non-contrast CT:

  • Cortex: sharply hyperdense

  • Bone marrow: relatively hypodense compared to cortex

  • Excellent for fractures, cortical irregularities, bone loss, or sclerosis

CT Post-Contrast:

  • Bone: unchanged

  • Adjacent soft tissues and vascular structures: enhanced, allowing evaluation of infection, hematoma, or tumor extension

  • 3D CT reconstructions aid in pelvic trauma and orthopedic surgery planning

CT VRT 3D image

Body of ischium 3D ct vrt image

CT image

Body of ischium ct axial image

MRI image

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