Translations:Kreuz- und Steißbein/2/en

The sacrum (Os sacrum) is a triangular bone and originally consists of five independent sacral vertebrae (Vertebrae sacrales, S1-S5).

It was formed by the fusion of the five cross vertebrae and the intermediate intervertebral discs (Discus intervertebrales). It belongs to the immobile part of thespine. The sacrum has a forward concave surface (Facies pelvina), the dorsal surface (Facies dorsalis) is convex. The tip of the sacrum (Apex ossis sacri), positioned caudally, is connected to the coccyx. Dorsally of the sacrum, there are five bone ridges (longitudinal ridges), which emerged from the spinous, articular and transverse processes. Between the foramina sacralia anteriora are the four transverse lines of the fused vertebral bodies (line transversae). Furthermore, the passage (Foramina sacralia pelvina) for the spinal cord nerves (spinal nerve) is located there.