The posterior serratus muscle is on the back, roughly at the bottom of the ribcage. As relayed by Adam McCalvy of MLB.com, it’s rare for a baseball player to strain this muscle, which means the ...

The serratus anterior muscle inserts exactly at the front border of the scapula, or shoulder blade. The muscle has three sections: the superior, intermediate or medial, and the inferior.

The Serratus anterior (SA) isn’t the easiest muscle to work on. That’s mainly because its function doesn’t exactly revolve around contracting and moving a joint through range of motion.