How many fused vertebrae make up the sacral region of the spine?

The sacral region of the spine consists of five fused vertebrae. These vertebrae, identified as S1 through S5, are progressively fused together during early adulthood to form a single triangular-shaped bone known as the sacrum. This fusion provides stability and strength to the pelvis and serves as an essential connection point for the spine to the iliac bones of the hip. The sacrum plays a vital role in supporting the weight of the upper body when sitting and standing, as well as providing protection to the pelvic organs. Understanding this anatomical structure is key in studying spinal anatomy and its functional significance in the human body.