What is Serratus Anterior?

What is Serratus Anterior?

The serratus anterior is a broad, fan-shaped muscle that wraps around the side of your rib cage, tucked between the ribs and the shoulder blade. Its name comes from its serrated, saw-tooth appearance where it grips the upper ribs - in lean, muscular people you can see these finger-like slips just below the armpit, above the ribs. It is nicknamed the "boxer's muscle" because it powers the forward reach of a punch, driving the shoulder blade forward around the rib cage. Anatomically it is the main muscle connecting the scapula to the rib cage from the front, and it plays two jobs most lifters underrate. First, it holds the shoulder blade flat and stable against the thorax; when it is weak or its nerve is injured, the inner edge of the scapula lifts off the back in the classic "winged scapula." Second, together with the trapezius, it rotates the shoulder blade so the socket points upward - the motion that lets you lift your arm above shoulder height without impingement. That makes the serratus anterior essential for all overhead pressing, handstands, and reaching tasks. Because it sits deep and does not create an obvious "beach muscle" look on its own, it is easy to neglect, yet it is one of the most important muscles for healthy, pain-free shoulders. Any time you push something away from you, reach forward, or press overhead, the serratus anterior is coordinating the position of the shoulder blade so the arm has a stable base to work from.

How it works

The serratus anterior works by pulling the medial border of the scapula forward and around the curve of the rib cage. It originates as a series of fleshy slips from the outer surfaces of roughly the first through eighth or ninth ribs on the side of the chest, then passes backward deep to the scapula to insert along the whole length of the costal (rib-facing) surface of the scapula's medial border - with a particularly strong concentration of fibres at the inferior angle. Because of this line of pull, contraction produces protraction: the scapula slides forward around the ribs, as in a punch, a push-up at the top when you push your upper back away, or a bench-press lockout. The lower fibres, pulling on the inferior angle, are the key upward rotators: they swing the bottom of the scapula outward and forward so the glenoid socket tilts upward, which is what allows the arm to elevate past about 90 degrees. This upward rotation is a partnership - the serratus anterior works with the upper and lower trapezius as a force couple to rotate the scapula smoothly during overhead motion. A third crucial role is stabilisation: the serratus anterior continuously holds the scapula flush against the thoracic wall, resisting the winging that would otherwise occur during pushing. Its nerve supply is the long thoracic nerve, arising from the C5, C6, and C7 roots; this nerve runs a long, exposed course down the side of the chest, which is why it is vulnerable to injury and why serratus weakness and scapular winging are relatively common clinical findings. In the gym, the serratus is recruited strongly by pressing and push-up variations, especially the "push-up plus" where you add a final protraction at the top, and by overhead work that demands upward rotation. EMG studies of scapular exercises confirm that push-up-plus and reaching movements produce high serratus anterior activity, which is why they are staples of both training and shoulder rehab.

How to apply it

• Push-up plus: Perform a push-up, then at the top actively push your upper back toward the ceiling so the shoulder blades spread apart. That final protraction is where the serratus works hardest. Do 8-15 controlled reps, keeping the plus range deliberate rather than bouncing.
• Overhead pressing: Any overhead press - barbell, dumbbell, or landmine - demands upward rotation from the serratus anterior. Press through a full range and let the shoulder blades rotate up naturally; do not fight to pin them down. Train in the 5-10 rep range.
• Scapular wall slides: Standing with forearms on a wall, slide them up and overhead while keeping contact and reaching long at the top. This trains upward rotation and protraction under light load - ideal as warm-up or rehab work for 10-15 slow reps.
• Serratus punches and reaches: Lying on your back or in a plank, press a light weight or your bodyweight up and reach the shoulder forward at the end. This isolates protraction. Use light load and high reps (12-20) to build control and end-range strength.
• Carries and plank protraction: Overhead carries and plank variations where you push the floor away train the serratus to stabilise the scapula against load and fatigue. Hold strong protraction and keep the shoulder blades flat, not winging, throughout the set.
• Train the full overhead range: The serratus only earns its upward-rotation strength if you take the arm fully overhead. Restricting yourself to partial ranges or avoiding overhead work leaves it weak, which can undermine shoulder health and press performance over time.

Types

Worked example

A shoulder-friendly session that trains the serratus anterior through its two main jobs - protraction and upward rotation - plus stability work. It pairs pressing strength with lighter control drills, which is how the serratus is best developed for both performance and shoulder health.

Heavier upward-rotation work (overhead press) leads while you are fresh; protraction and stability drills follow. If the inner edge of a shoulder blade wings out during push-ups or planks, reduce the load or range until you can keep it flat - that winging is exactly what serratus training fixes.

Serratus anterior vs rhomboids

The serratus anterior and rhomboids are antagonists that move the scapula in opposite directions. Both must be strong and coordinated: the serratus protracts and upwardly rotates, the rhomboids retract and downwardly rotate, and together they control every position of the shoulder blade.

By goal

• Overhead athletes: Throwers, swimmers, and pressers rely on serratus upward rotation for safe arm elevation. Prioritise push-up-plus work, wall slides, and full-range overhead pressing to keep the scapula rotating well and reduce impingement risk under repeated overhead load.
• Hypertrophy-focused lifters: The serratus adds detail to a lean torso - the visible finger-like slips below the armpit. Train it with push-up-plus, dumbbell pullovers, and reaching movements in the 10-20 rep range, focusing on a strong end-range protraction each rep.
• Shoulder rehab: Serratus weakness and scapular winging are common in shoulder pain. Start with low-load protraction and wall-slide drills to restore upward rotation before loading overhead. Progress only when the scapula stays flat and rotates smoothly without winging.

Common misconceptions

• "The serratus anterior is a core or ab muscle." Its serrated slips sit on the side of the rib cage near the obliques, so it is often mistaken for an ab muscle. It is actually a scapular muscle: its job is to move and stabilise the shoulder blade, not to flex or rotate the trunk.
• "You should always pull your shoulder blades back and down." Constant forced retraction fights the serratus. When you press or reach overhead, the scapula needs to protract and upwardly rotate freely. Locking the shoulder blades back at all times can actually impair healthy overhead mechanics and overload other tissues.
• "The serratus can't be trained directly." It responds well to targeted work. Push-up-plus, serratus punches, wall slides, and full-range overhead pressing all bias the serratus anterior. It is one of the most trainable and rehab-responsive scapular muscles when you emphasise end-range protraction and upward rotation.
• "A winged scapula is just poor posture." Winging can come from serratus weakness, but true winging often reflects long thoracic nerve dysfunction affecting serratus function. It deserves proper assessment rather than being dismissed as slouching - the fix depends on whether the cause is muscular or neurological.

Related terms

Serratus Anterior FAQ

What is the serratus anterior?

The serratus anterior is a fan-shaped muscle on the side of the rib cage running from the upper ribs to the underside of the shoulder blade's inner border. It protracts and upwardly rotates the scapula and holds it flat against the ribs. It is nicknamed the boxer's muscle.

What does the serratus anterior do?

It pulls the shoulder blade forward around the rib cage (protraction), rotates it so the socket tips upward to let you raise your arm overhead, and stabilises the scapula against the thoracic wall. It powers pushing, reaching, punching, and overhead pressing.

Why is it called the boxer's muscle?

Because it drives the forward reach of a punch. When you throw a straight punch, the serratus anterior protracts the shoulder blade to extend the arm and shoulder forward, adding reach and power. That distinctive action earned it the boxer's-muscle nickname.

What is the best exercise for the serratus anterior?

The push-up plus is the classic choice: perform a push-up, then push your upper back toward the ceiling at the top to protract the shoulder blades. Full-range overhead pressing and scapular wall slides also strongly train the serratus's upward-rotation role.

What causes a winged scapula?

A winged scapula - where the inner edge of the shoulder blade lifts off the back - usually results from serratus anterior weakness or dysfunction of its nerve, the long thoracic nerve. Because that nerve has a long, exposed course, it is relatively prone to injury.

Where is the serratus anterior located?

It sits on the side of the rib cage, deep to the scapula and pectoral muscles, wrapping from the outer surfaces of the upper 8-9 ribs to the inner border of the shoulder blade. In lean people its saw-tooth slips are visible just below the armpit.

What nerve supplies the serratus anterior?

The long thoracic nerve, which arises from the C5, C6, and C7 nerve roots, supplies the serratus anterior. It runs a long, superficial course down the lateral chest wall, making it vulnerable to injury that can weaken the muscle and cause scapular winging.

How do I fix a weak serratus anterior?

Start with low-load protraction and upward-rotation drills - push-up plus, serratus punches, and wall slides - focusing on a strong end-range reach and keeping the shoulder blade flat. Progress to full-range overhead pressing once the scapula moves smoothly without winging.

References

1. Anatomy, Thorax, Serratus Anterior Muscles. StatPearls, NCBI Bookshelf
2. Anatomy, Thorax, Long Thoracic Nerve. StatPearls, NCBI Bookshelf
3. Ekstrom RA, Donatelli RA, Soderberg GL. Surface electromyographic analysis of exercises for the trapezius and serratus anterior muscles. J Orthop Sports Phys Ther, 2003. PubMed 12774999
4. Kim SH, et al. Comparison of the Effects of Isometric Horizontal Abduction on Shoulder Muscle Activity During Wall Push-Up Plus and Wall Slide in Individuals With Scapular Winging. J Sport Rehabil, 2023. PubMed 36689994