Bony pelvis

The pelvic skeleton is composed of two hip bones, sacrum, and coccyx.

The three bones fuse together during puberty and ossify around age 25. The left and right hip bones join in the pubic symphysis.

  • Sacrum - a triangular-shaped bone at the base of the spine, which is formed by 5 sacral vertebrae that are fused with each other (it happens between ages 18 to 30).
  • Coccyx - also known as the tailbone, the final bony segment of the spine, which consists of 3 to 4 rudimentary vertebrae fused together.