Muscle guide · Chest and shoulders
Also called boxer's muscle, serratus
The serratus anterior is a fan of finger-like slips on the side of the rib cage, from the upper eight or nine ribs back to the inner edge of the shoulder blade. Most of it lies hidden under the shoulder blade and the chest muscles.
It pulls the shoulder blade forward around the ribs, as in throwing a punch, which is why it is called the boxer's muscle, and with the trapezius it turns the shoulder blade upward so you can lift your arm overhead.
The push-up plus and the 'dynamic hug' produced the most serratus activity of eight exercises below shoulder height; serratus punches and scaption were also strong. Raising the arm in the scapular plane above 120 degrees activated it maximally.
Weakness of the serratus, usually from injury to its long, exposed nerve, is the most common cause of a shoulder blade that sticks out from the back. Causes include surgery in the armpit, pressure from heavy backpack straps or crutches, heavy loads, and unaccustomed digging. Strain-related cases usually recover over 6 to 24 months.
Work up to full push-ups: wall, incline and knee push-ups, then the floor push-up and harder variations.
15 minBeginner8 movesA wall, A bench or boxA 10-minute routine for a stiff upper back and rounded shoulders: chin tucks, wall angels, Y-T-W raises and open books.
10 minBeginner7 movesA foam roller, A wallIt pulls the shoulder blade forward around the ribs, turns it upward so the arm can go overhead, and holds it flat against the rib cage.
The push-up plus, a push-up with an extra push at the top, produced the most activity in an EMG study of eight exercises.
The most common cause is weakness of the serratus anterior, usually from injury to its nerve. Get it assessed if it appears suddenly or with weakness.
Anatomy and movement education, not a diagnosis or treatment plan. If you have pain that follows an injury, is severe or getting worse, or comes with numbness, weakness or swelling, get it assessed. Health disclaimer.
