Superior Articular Process Of The Sacrum

Description

Sacral superior articular processes rise from the dorsolateral base of the sacrum at the level of S1, bordering the posterior aspect of the sacral canal. From a posterior view, each process appears as a pointed bony eminence with an articular facet oriented superiorly and medially to meet the inferior articular facet of L5 at the lumbosacral zygapophysial joint. Lateral to the processes, the sacral ala flares toward the iliac articulation, while the midline falls toward the median sacral crest formed by fused spinous processes. Orientation is unambiguous. Facet morphology at S1 matters because it anchors stability at L5 to S1, the junction that absorbs high shear forces during flexion and axial loading. Degenerative facet arthropathy, pars interarticularis defects, and isthmic spondylolisthesis often localize their pain generators and surgical targets around this articulation, and subtle variation in facet angle can influence both instability patterns and screw trajectory planning. The posterior lighting and isolation of the superior articular facet in this illustration supports teaching of surface contours that are palpated and exposed during posterior lumbar approaches, without distracting anterior pelvic landmarks. Use this illustration in gross anatomy and osteology labs when differentiating sacrum from lumbar vertebrae and when teaching the lumbosacral zygapophysial joints in a spine block. It also fits well in orthopedic and neurosurgical education materials covering lumbosacral fusion, facet-mediated back pain, and preoperative planning discussions that reference posterior bony landmarks. Anatomical accuracy verified by SciePro's Medical Advisory Board.