Which structure is responsible for protecting the brain?

The skull is primarily responsible for protecting the brain. It is a bony structure that encases the brain and provides a physical barrier against external impacts, physical trauma, and infections. Made up of several bones fused together, the skull not only shields the delicate brain tissue but also serves to support the structures of the face and provides attachment points for muscles involved in head movement and facial expressions.

Other structures listed play different roles within the body. The spine, while crucial for protecting the spinal cord and providing structural support, does not cover the brain directly. The rib cage protects the heart and lungs, offering a shield for the thoracic organs rather than the brain. The mandible is the lower jawbone, which primarily assists in the functions of chewing and forming the structure of the face, but it does not contribute to brain protection. Thus, the skull is the most appropriate answer in the context of safeguarding the brain.