what is sacrum
Sacrum. The sacrum is the name of the bone located at the base of the spine that consists of five fused vertebrae. These vertebrae are unfused in children, but by the early to mid twenties, they will be fused together. It is triangular in shape and connects the final lumbar vertebra with the coccyx, which is commonly referred to as the tailbone. The sacrum is curved, which allows more room in the pelvic cavity for various organs.