Iliac Crest Showing Its Position In The Pelvic Girdle, Posterior View

Description

Iliac crest anatomy is centered on the posterior rim of the ilium, with the crest curving laterally and anteriorly from the posterior superior iliac spine (PSIS) toward the iliac tubercle and anterior superior iliac spine. From this posterior perspective, the PSIS and posterior inferior iliac spine (PIIS) sit medial to the posterior iliac crest, while the sacrum lies immediately medial and inferior, forming the posterior boundary of the pelvic girdle at the sacroiliac region. The outer (gluteal) surface of the ilium faces posterolaterally, and the inner (iliac fossa) surface is largely obscured from this viewpoint. Bony landmarks dominate. Posterior iliac crest landmarks matter because clinicians palpate the PSIS routinely to estimate spinal level (often approximating S2), to orient lumbar puncture planning, and to localize sacroiliac joint pain generators. The crest also serves as a common donor site for autologous bone graft and bone marrow aspiration, where the thickness of the posterior ilium and proximity of the sacroiliac joint, superior cluneal nerve branches, and gluteal musculature drive safe trajectory and patient counseling. Broad tendon and fascial attachments converge here, including the thoracolumbar fascia and the origin of gluteus maximus along the posterior iliac crest, relationships that help explain pain patterns in posterior pelvic enthesopathy and postoperative donor-site tenderness. Use this illustration for musculoskeletal anatomy teaching in pelvic girdle and hip modules, for orthopedic and spine surgery texts discussing iliac crest graft harvest, and for pain medicine or physical therapy materials addressing PSIS palpation and sacroiliac joint localization. Anatomical accuracy verified by SciePro's Medical Advisory Board.