You're not alone if—even with a bank of multiple-choice answers—you have absolutely no clue what the serratus anterior muscle is, let alone where it is in your body. 

But once you read this, you're absolutely gonna want to hone yours. The serratus muscle spans over the top of your eight or nine upper ribs. When your body fat is low enough, they'll look like fingers pointing from your ribs to your six-pack. Raise your arms, and you might be able to see yours.

Aside from making your physique look especially shrink-wrapped and shredded, the serratus is vital for healthy shoulders; it acts as a stabilizer. To boost yours, do 10 to 20 reps of any of the following moves before your regular workout.

1. Dip shrug
Get on parallel bars as you would for dips. Keeping a slight bend in your elbows, let your body sink down between your shoulders (it'll look like you're shrugging), then spread your shoulders and rise as much as you can. Your arms shouldn't move.

2. Scapular pushup
Get into pushup position and lower your body between your shoulders without bending your elbows (you'll only move a few inches). Then spread your shoulders to come up. Be sure to keep your core braced throughout. It's the same idea as the dip shrug.

3. One-arm split-stance cable press
Attach a D-handle to a cable pulley and hold it at chest height. Get into a lunge position. Press the handle forward, keeping your shoulders square with your hips.