Lateral Part Of The Sacrum

Description

Sacral ala (lateral part of the sacrum) dominates the frame as the broad lateral mass formed by fusion of the sacral transverse processes, expanding laterally from the sacral body toward the sacroiliac region. The auricular surface lies on the posterolateral aspect, positioned lateral to the anterior sacral foramina and superior to the posteroinferior roughened area that continues into the sacral tuberosity. Superiorly, the ala approaches the base of the sacrum at S1 and the lumbosacral junction, while inferiorly it tapers toward the lateral margin adjacent to the lower sacral segments. Bony relief is the point. Sacroiliac joint anatomy often becomes abstract in text, yet the lateral sacrum is where ligamentous stability and load transfer concentrate, and this illustration keeps the auricular surface and adjacent roughened attachment zones readable for teaching. Pain generators such as sacroiliitis (including ankylosing spondylitis) and degenerative SI arthropathy localize to this interface, and sacral insufficiency fractures commonly involve the sacral ala, producing lateral sacral pain that can mimic lumbar radiculopathy. For procedural planning, the lateral mass is also the corridor for iliosacral screw fixation; appreciating the thickness of the ala and its relationship to the sacral foramina helps reduce the risk of violating the neural foraminal space. Use this illustration in pelvic anatomy labs, spine modules covering the axial skeleton, and surgical education on posterior pelvic ring injury fixation, where orientation to the sacral wing (ala) and the sacroiliac articular region matters more than midline features. It also fits well in radiology teaching files as a pre-imaging anatomic reference for CT evaluation of sacral ala fractures and SI joint inflammatory change. Anatomical accuracy verified by SciePro's Medical Advisory Board.