What is the sacrum?
It is called the sacrum. Gray's Anatomy (1918) describes it as a large, triangular bone made from the fusion of five sacral vertebrae.
What it is
- A large, triangular bone made from the fusion of five sacral vertebrae.
- Forms the back wall of the pelvis.
- Transmits the weight of the upper body to the hip bones.
Where it is
- Between the two hip bones.
- Below the lumbar spine and above the coccyx.
- Joins each hip bone at the sacroiliac joint.
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Last verified: 2026-07-18
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