The sacrum is defined as?

• A. Tailbone
• B. Nerve bundle inside vertebral canal
• C. Fused vertebrae forming pelvis base
• D. Distributive shock from spinal cord injury causing vasodilation

Answer: (C)

The sacrum is a fused bone at the base of the spine. It results from the fusion of five sacral vertebrae, forming a single structure that sits between the two ilia to complete the posterior part of the pelvic ring and help transfer body weight into the pelvis. This fusion and pelvic position distinguish it from other structures. The name “tailbone” refers to the coccyx, the small bone at the very end of the spine, not the sacrum. A nerve bundle inside the vertebral canal would be the spinal cord or cauda equina, not the sacrum itself. Distributive shock is a circulatory condition, not a bone description.