Coccygeal Horn On The Coccyx

Description

Coccygeal cornu (coccygeal horn) projects superiorly from the dorsal aspect of the first coccygeal vertebra (Co1) along the posterior margin of the tailbone. From a fixed lateral perspective, the horn sits just inferior to the sacral apex, adjacent to the sacrococcygeal joint line, while the remaining coccygeal segments taper inferiorly and slightly anteriorly toward the coccygeal tip. Anterior to the cornua, the smooth pelvic surface of the coccyx curves toward the pelvic outlet, and posteriorly the bony contour thickens where dorsal ligaments and fascia attach. Small structure. Reliable landmark. Anatomically, the coccygeal cornua frame the posterior boundary of the sacrococcygeal region and complement the sacral cornua, a relationship that helps orient the inferior end of the sacral canal and the sacrococcygeal ligament complex during surface anatomy correlation. Coccygeal morphology varies, but prominence or asymmetry at Co1 can become clinically relevant in coccydynia, post-traumatic malalignment after a fall onto the buttocks, postpartum coccygeal pain, or degenerative change at the sacrococcygeal joint that may be palpable on rectal examination. The lateral viewpoint makes the superior-inferior alignment of the cornu relative to the first coccygeal body easy to read, which supports teaching of why a small dorsal projection can still act as a focal point for tenderness and for ligamentous traction from the pelvic floor. Use this illustration in gross anatomy and musculoskeletal modules covering the pelvic outlet, in radiology teaching files when correlating lateral pelvic radiographs or sagittal CT reconstructions, and in pain medicine materials discussing coccygeal tenderness and image-guided injection planning near the sacrococcygeal junction. Anatomical accuracy verified by SciePro's Medical Advisory Board.