There are no muscles inside the cranium, as you have admitted. You may THINK your brains are moving around, but they are
not. They are just sitting there. Electrical impulses, however, can be felt. Some people who take SSRI drugs, for example, if their dose drops they sometimes feel a brain zap or hum inside their skull. Arteries inside there, too, can be felt when they goof up, in the form of certain types of headaches, for example.