What are muscles that you cannot control consciously?

These muscles are called "involuntary" muscles, because you cannot consciously control them. The most well-known of these muscles is the heart, but involuntary muscles control the digestive process (peristalsis-- moving food through your system) as well. You can't consciously make your heart stop or start, and you can't control the process by which food moves through the digestive tract. Some functions, like breathing, are controlled by both voluntary and involuntary muscles. You can breathe, in fact almost always breathe, without thinking about it. But you can also hold your breath, like when you are underwater. So the process of breathing, which is controlled in part by a large muscle known as the diaphragm, is both voluntary (because you can stop it to a point) and involuntary (because it goes on unconsciously). Involuntary movements of voluntary muscles can also occur during some stages of sleep.