Which structure of the brain is responsible for maintaining balance and motor coordination?

The cerebellum is the structure of the brain specifically responsible for maintaining balance and coordinating motor activities. It plays a crucial role in fine-tuning movements, allowing for smooth and precise motor skills. The cerebellum processes sensory information about body position and movement, integrating this data to help control posture and balance. This allows an individual to perform tasks that require coordination, such as walking, writing, or playing an instrument.

The other structures mentioned serve different functions. The medulla controls autonomic functions such as breathing and heart rate; the midbrain is involved in processes such as vision and hearing and in regulating motor functions; while the cerebral cortex is key in complex cognitive functions, including reasoning, language, and decision-making. None of these structures are primarily responsible for balance and motor coordination, which reinforces why the cerebellum is the correct answer.