When you have muscles

Here's something I bet you never realized about muscles: when you have them, you can pull them.

For the first time in my life, I pulled a muscle in my chest. I kid you not. Who pulls a chest muscle? I was in a triangle pose, stretching my hamstring, and decided to move into reverse triangle pose. When I shifted to drop my hand to the floor to loosen my hips, a muscle in my chest pulled.

It affects me only when I try to move into that pose again and when I try to do pullups. I can still throw fine. But still. Who pulls a chest muscle? And since when do I have chest muscles?