Bicep and tricep muscles
Finding out information about what is going on inside the body is a critical part of diagnosing disease and injury. Today's medical imaging techniques allow us to do this. They have given us an understanding of how the human body functions. For example how groups of muscles work together.
Seen here is the bicep and tricep muscles. When the bicep muscle contracts to flex (bend) the forearm, the triceps muscle relaxes. To extend (straighten) the forearm the biceps relaxes and the triceps contracts.