What coordinates muscular activity in the brain?

The cerebellum, the nervous system and oxygenated blood. A stroke can stop many areas of the brain from functioning properly because it must have oxygen, water, blood, nutrients, and hormones to keep it working correctly. The nerves will be affected too. That is why you see paralysis often on people who suffer strokes. When there are tumors they can affect the entire body and the brain muscles or functions.