What is the function of the sacrum?

• A. To protect the brain
• B. To support the upper limbs
• C. To facilitate breathing
• D. To strengthen and stabilize the pelvis

Answer: (D)

The sacrum mainly acts to strengthen and stabilize the pelvis by forming the back portion of the pelvic ring and transferring body weight from the spine down to the hips and legs. It’s a triangular bone made from fused vertebrae and connects to the ilia through the sacroiliac joints, anchoring muscles and ligaments that support posture and movement. This stabilizing role is central to how the pelvis bears load and allows efficient transfer of forces during activities.

The other options don’t fit this function: protecting the brain is the job of the skull; supporting the upper limbs is the responsibility of the shoulder girdle; and aiding breathing involves the rib cage and diaphragm.