Which functions as a protective structure for the brain?

The skull functions as a protective structure for the brain by providing a hard, bony encasement that safeguards it from physical trauma and injury. This intricate structure consists of both the cranial bones which form a protective box around the brain and the facial bones. The design of the skull not only protects the brain from external impacts but also supports the structures of the face, allowing for essential sensory functions and protection of the underlying neural tissues. Its shape and strength are specifically adapted to absorb and distribute forces, further enhancing the brain’s safety.

The other options, while all parts of the body, are not involved in direct protection of the brain. The pelvis protects vital organs in the lower body, while the humerus and tibia are long bones that support and enable movement in the arms and legs, respectively. None of these structures have the primary function of safeguarding the brain as the skull does.