Arcuate Line Of The Ilium On The Surface Of The Hip Bone, Medial View

Description

Arcuate line (linea arcuata) on the medial surface of the ilium forms a smooth, curved ridge that runs anteroinferiorly from the region of the auricular surface toward the iliopubic (iliopectineal) eminence. Medially and inferiorly, it aligns with the pectineal line of the superior pubic ramus to complete the iliopectineal line, the bony contour that defines much of the pelvic brim (linea terminalis). Posterior to it, the iliac fossa opens broadly, while the sacropelvic surface of the ilium and the margin of the greater sciatic notch sit more posteroinferior. Short and unmistakable. Obstetric pelvimetry and pelvic fracture classification both depend on this landmark because the arcuate line marks the transition between greater (false) pelvis superiorly and lesser (true) pelvis inferiorly, effectively outlining the pelvic inlet in combination with the sacral promontory and pubic crest. A medial perspective on the internal surface makes the slope and curvature easy to read against adjacent nonarticular bone, which helps when teaching students to distinguish the arcuate line from nearby ridges and impressions that can be confused in dry bone handling or in simplified diagrams. For surgeons and radiologists, correlating this ridge with the pelvic brim also supports orientation when discussing ring injuries that involve the ilium and superior pubic ramus, where “above” versus “below” the pelvic brim changes the language around pelvic inlet compromise. Use this illustration in gross anatomy labs, osteology practicals, and obstetrics and gynecology teaching materials that introduce the pelvic inlet, linea terminalis, and the false versus true pelvis distinction. It also suits orthopedic and trauma publications that need a precise bony reference for pelvic brim terminology on the os coxae. Anatomical accuracy verified by SciePro's Medical Advisory Board.