This questions is slightly difficult to answer, as we scientists are not completely clear on what a muscle is. The muscles we traditionally think of as ‘muscles’ are known as skeletal muscles. These are the ones that move your limbs, and are usually attached to bones via tendons. Even estimates for these range from 600-800 muscles.
Now we have microscopes and better ways of seeing inside the body, we have found many other types of muscle like structures. For example, every hair on your body has a tidy muscle at the base of it – these are what contract when your ‘hairs stand on end’ – they are what make goosebumps. That is about another 5 million muscles. There are also muscles that make you blink, focus your eyes… your heart is a muscle too