Anatomical Characteristics Of Auricular Surface Of The Sacrum

Description

Facies auricularis ossis sacri occupies the superolateral aspect of the sacrum, an ear-shaped articular area that faces laterally toward the ilium at the sacroiliac joint. Along its anterior margin, the sacral ala (ala ossis sacri) broadens superiorly toward the base and promontory, while posteriorly the surface approaches the roughened dorsal sacral region where ligamentous attachments cluster. Inferior to the auricular surface, the lateral border narrows toward the apex, with the anterior sacral foramina positioned medial to the articular zone and the transverse ridges of fused sacral vertebrae forming subtle contours on the pelvic surface. Texture matters here. Clinically, the auricular surface is the bony half of the sacroiliac articulation, where hyaline cartilage on the sacral side meets fibrocartilage on the iliac side, and where small variations in curvature and ridging influence load transfer from the axial skeleton into the pelvis. Pain generators often localize to this joint in postpartum pelvic girdle pain, degenerative sacroiliitis, and inflammatory spondyloarthropathies such as ankylosing spondylitis, so understanding where the auricular surface sits relative to the sacral ala and sacral foramina helps when correlating provocative tests, fluoroscopic joint injections, or CT-guided interventions. The single, fixed perspective emphasizes the contrast between the smoother articular facies and the adjacent roughened bone that anchors the anterior sacroiliac, interosseous, and posterior sacroiliac ligaments. Use this illustration in gross anatomy and osteology teaching to orient learners to the sacrum’s lateral anatomy, and in radiology or pain medicine materials to annotate the sacroiliac joint line, typical enthesopathy sites, and nearby foraminal landmarks. It also suits orthopedic and spine surgery publications discussing sacroiliac fixation trajectories and safe corridors relative to the pelvic surface. Anatomical accuracy verified by SciePro's Medical Advisory Board.