Ala Of The Sacrum, Anterior View

Description

Sacral ala (ala ossis sacri) occupies the superolateral margin of the sacrum on its pelvic, anterior surface, flaring laterally from the body of S1 toward the iliac articulation. Medial to the ala, the anterior surface of the sacral body shows the sacral promontory superiorly and the smooth pelvic surface marked by transverse ridges that indicate fusion of the sacral vertebrae. Inferior and slightly lateral to the promontory, the anterior sacral foramina align in paired rows, providing passage for the anterior rami of sacral spinal nerves and accompanying vessels. Orientation is fixed in an anterior view, so the ala reads as a broad wing framing the pelvic inlet laterally. Alar anatomy matters in both trauma and fixation because fractures at the sacral ala can destabilize the pelvic ring while sparing the midline, and their relationship to the anterior sacral foramina influences neurologic risk. In iliosacral screw placement for posterior pelvic ring injuries, the safe corridor is constrained by the sacral ala laterally and the neural foramina medially, a relationship that can be hard to visualize without a clean pelvic-surface reference. Sacral dysmorphism also changes the alar slope and the outline of the sacral promontory, which affects fluoroscopic landmarks and helps explain why some patients have higher rates of screw malposition. Small structure, big consequence. For teaching, this illustration supports gross anatomy of the pelvis, osteology practicals, and lumbosacral junction modules where learners must distinguish the pelvic surface from the dorsal surface and recognize the alae in relation to the pelvic brim. It also fits orthopedic trauma texts, radiology atlases discussing sacral ala fractures on CT, and preoperative planning material for sacroiliac fixation where precise spatial relationships are the point. Anatomical accuracy verified by SciePro's Medical Advisory Board.