Lower limb
Hip bone
Os coxae
- Origin
- Formed by fusion of ilium, ischium, and pubis meeting at the acetabulum
- Insertion
- Extensive origin for abdominal wall muscles, gluteal muscles, hip rotators, and pelvic floor
- Function
- Transfers axial load from vertebral column through sacroiliac (SI) joints to the lower limbs; encloses pelvic viscera
- Innervation
- Lumbar and sacral plexuses (L1–S4)
- Movement & chain
- Pelvic tilt (anterior/posterior), lateral pelvic drop, and nutation/counternutation at SI joints
- Palpation
- Iliac crest, ASIS, PSIS, ischial tuberosity, and pubic symphysis are prominent landmarks
- Clinical
- High-energy pelvic ring fractures with hemodynamic instability; SI joint dysfunction; apophyseal avulsions in adolescent athletes
- Segmental innervation
- L1–S4
- In clinical practice
- Jacoby's line (iliac crests) identifies L4 spinous process for lumbar puncture; safe quadrant for IM gluteal injections
- Region in the model
- Lower limb