Serratus Anterior Muscle – Anatomy Breakdown & Clinical Relevance

Jul 20

The Serratus Anterior is a flat, powerful muscle that wraps around the ribcage and plays a critical role in scapular stability, protraction, and upward rotation. Though often overlooked, it's essential for pain-free shoulder mechanics and overhead movement. In this video, Treadwell, DPT breaks down the origin, insertion, function, innervation, and clinical relevance of the Serratus Anterior—plus evidence-based rehab insights.

If you’re a student, clinician, or just someone working through shoulder dysfunction, this one's for you.

Quick Hits

The Serratus Anterior originates on the outer surfaces of the first 8 or 9 ribs, and inserts onto the anterior surface of the medial border of the scapula. It’s often called the Boxer’s Muscle due to its contribution to punching movements and the distinctive “serrated” appearance along the ribs in lean, well-trained individuals.

Origin: Outer surfaces of ribs 1–8 (variable to 9 or 10)
Insertion: Medial border of the anterior scapula
Innervation: Long thoracic nerve (roots C5–C7)
Actions: Protraction of the scapula, upward rotation, fixation of scapula to thoracic wall

Its orientation allows it to pull the scapula snug against the thoracic cage and rotate it upward during arm elevation—key for healthy shoulder movement.

Clinical Relevance

Weakness or inhibition of the Serratus Anterior can lead to scapular winging, overhead movement dysfunction, and shoulder impingement. Patients may compensate with upper traps and levator scapulae, worsening posture and pain.

Common clinical patterns include:

Visible scapular winging
Difficulty with overhead tasks
Poor scapular control
Postural deficits (upper crossed syndrome)

The wall push-up test is a reliable tool to assess Serratus function. Rehab programs should prioritize high-activation, low-compensation movements. According to EMG studies, the push-up plus, serratus punch, wall slide with resistance, and dynamic hug are some of the most effective exercises.

𖤓 “If you're not training the Serratus, you're not fixing the shoulder.”