The sacrum is the lower most segment of the vertebral column and also forms the posterior wall of the bony pelvis. The sacrum is formed by five fused sacral vertebrae.
The sacrum is formed by fusion of five sacral vertebrae has three surfaces, a base and an apex. The body of the first segment is large and is similar to lumbar vertebra whereas the bodies of the next bones get progressively smaller, are flattened from the back, and curved to shape.
The sacrum articulates with four other bones – iliac bones on either side, L5 above and coccyx below. It is tilted forward and curved with anterior concavity and posterior convexity allowing greater room for pelvic cavity. The curvature of sacrum varies in individuals.
This 3D model was created from the file STS_037
The original CT examination can be reviewed at: