Serratus Anterior: The Forgotten Muscle

Serratus Anterior: The Forgotten Muscle

 

 

Serratus Anterior: The Forgotten Muscle

By Anna Staehli Wiser, DPT, FAAOMPT

The serratus anterior is an often-overlooked muscle that plays a vital role in shoulder health and upper body function. Located along the upper sides of the thorax, it attaches from the first eight or nine ribs to the anterior surface of the scapula’s medial border. Though it functions quietly behind the scenes, its contribution to proper shoulder mechanics is anything but minor.

 

 

What Does the Serratus Anterior Do?

The primary role of the serratus anterior is to stabilize the scapula (shoulder blade) against the rib cage. This anchoring effect allows for efficient upward rotation and protraction of the scapula—movements critical for lifting the arm overhead.

When functioning properly, the serratus anterior ensures that shoulder movement is smooth and coordinated. When weakened or dysfunctional, however, it can lead to scapular winging, where the inner edge of the scapula visibly lifts away from the thorax. This dysfunction is often implicated in shoulder impingement syndrome and other shoulder pathologies.

 

 

Why Is This Muscle Often Neglected?

Despite its significance, the serratus anterior is commonly forgotten in both clinical evaluations and exercise programs. Here’s why:

  • Difficult to Isolate: Unlike larger muscles such as the deltoid or trapezius, the serratus anterior is hard to strength-test in isolation.

  • Challenging to Target in Exercise: Many traditional shoulder workouts don’t effectively engage it.

  • Prone to Disuse and Atrophy: Poor posture, sedentary habits, and faulty movement patterns can cause it to weaken over time.

  • Vulnerable to Nerve Injury: The muscle is innervated by the long thoracic nerve, which runs a long and superficial course, making it susceptible to trauma—from falls, repetitive strain, or even awkward sleeping positions1,2.

 

 

Understanding Muscle Synergy: Force Couples in Action

Diagram source: Neumann, D. A. (2017). Kinesiology of the Musculoskeletal System: 

Foundations for Rehabilitation (3rd ed.). Elsevier.

This illustration shows the force couple between the serratus anterior (SA), lower trapezius (LT), middle trapezius (MT), upper trapezius (UT), and deltoid (DEL). These muscles must work in concert to produce upward scapular rotation—a key movement for reaching overhead. Among them, the SA and LT form the primary upward rotation team3.

 

 

The Serratus Anterior as a Pain Generator

While medial scapular border pain is typically associated with thoracic spine dysfunction or cervical referral, research has shown that myofascial trigger points in the serratus anterior can also refer pain to this region4. If you've experienced nagging, hard-to-localize pain near the inner edge of your shoulder blade, this often-overlooked muscle may be the culprit.

 

 

Rehabilitation: Why You Should Train the Serratus Anterior

For individuals with shoulder pain, weakness, or poor posture, targeted serratus anterior strengthening can be a game-changer. Incorporating specific exercises into your routine can help:

  • Restore shoulder mechanics

  • Reduce impingement symptoms

  • Improve postural control and stability

Key Tip: Exercises that combine shoulder depression and protraction are most effective in activating this muscle5.

 

 

Two Evidence-Based Exercises to Activate the Serratus Anterior

1. Foam Roller Wall Slides with Resistance Band

Instructions:

  • Loop a resistance band around your wrists.

  • Place forearms on a foam roller positioned against the wall.

  • Slide the roller upward while maintaining outward pressure on the band.

  • Keep your shoulder blades protracted and your core engaged throughout.

Why It Works:
 This closed-chain movement engages the serratus anterior, lower trapezius, and rotator cuff muscles synergistically.


2. Bear Crawl Rocking

Instructions:

  • Begin in a bear crawl position (hands and toes on the floor, knees lifted).

  • Rock your body gently forward and backward.

  • Keep your shoulders actively protracted as you shift your weight.

Why It Works:
This exercise encourages dynamic control of the scapula under load, increasing serratus anterior activation in a functional posture6.

 

 

Final Thoughts

Though often overshadowed by more prominent muscles, the serratus anterior is crucial for optimal shoulder function. Whether you're an overhead athlete or someone recovering from shoulder pain, don’t forget to include this “silent stabilizer” in your rehab and fitness plan. Strengthening it could be the key to unlocking pain-free, full-range shoulder motion.

 

 

Have questions?
Reach out to Dr. Wiser for guidance on incorporating serratus anterior exercises into your therapy or wellness routine.

 

 

References

1. Friedenberg ZB, Chevrot A. Long thoracic nerve palsy. Clinical Orthopaedics and Related Research. 2002;(403):29-33.

2. Pikkarainen S. Long thoracic nerve injury: A challenging diagnosis. Journal of Brachial Plexus and Peripheral Nerve Injury. 2013;8(1):e22-e27.

3. Neumann DA. Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation. Elsevier; 2017.

4. Fernández-De-Las-Peñas C. Trigger points in the serratus anterior muscle as a source of referred pain. Journal of Musculoskeletal Pain. 2005;13(3):27-35.

5. Cools AMJ, Struyf F, De Mey K, Maenhout A, Castelein B, Cagnie B. Rehabilitation of scapular dyskinesis: from the office worker to the elite overhead athlete. Br J Sports Med. 2014;48(8):692-697.

6. Decker MJ, Hintermeister RA, Faber KJ, Hawkins RJ. Serratus anterior muscle activity during selected rehabilitation exercises. Am J Sports Med. 1999;27(6):784-791.