Your arm muscles allow you to perform hundreds of everyday movements, from making a fist to bending your thumb. We’ll go over all the muscles in your upper arm and forearm as well as explain ...

Subscapularis is the largest and strongest of the rotator cuff muscles. It’s a triangular muscle on the front of the upper arm, beginning at the shoulder blade.

You could also see a big bulge in your upper arm. It will look like you have a huge biceps muscle. This is sometimes referred to as a “Popeye muscle” or “Popeye deformity.” ...