How many muscles are in the human body?

The gluteus maximus, in the buttock. The longest is the sartorius, which crosses the thigh. The smallest is the stapedius, inside the ear, just a few millimeters long.

Yes. It is made of cardiac muscle, a special kind that works on its own, without you telling it to, and doesn’t tire like arm and leg muscles.

A cramp is a strong, involuntary muscle contraction, very common in the calf. Muscle fatigue, staying in one position for a long time and intense heat are among the causes, but the reason isn’t always known. Gently stretching the muscle usually helps.

When a muscle works hard, its fibers get tiny injuries. With rest and good food, the body repairs those fibers and makes them a little thicker. That is why training needs recovery time.

Because a muscle can only pull, never push. To bend the arm, the biceps pulls; to straighten it, the triceps on the other side pulls. The same happens at almost every joint.