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Trapezius Muscle Overview

Sep 1, 2025

Overview

This lecture focuses on the anatomy and function of the trapezius muscle, common imbalances, and techniques to properly train and balance its different parts.

Trapezius Muscle Anatomy & Function

  • The trapezius muscle is often imbalanced, with the upper portion overdeveloped due to posture and daily activities.
  • The upper trapezius elevates the shoulders and is frequently tight from activities like driving and sitting.
  • The middle trapezius pulls the shoulder blades (scapulae) closer to the spine.
  • The lower trapezius pulls the shoulder blades down towards the spine.

Common Imbalances & Issues

  • Overuse of the upper trapezius can lead to shoulder and neck tightness, pain, and tension.
  • The middle and lower portions of the trapezius are usually weaker than the upper part.
  • Incorrect activation, such as pulling shoulders back instead of down, can worsen muscle imbalances.

Proper Shoulder Blade Positioning

  • Proper training begins with setting the shoulder blades by pulling them together and then down.
  • Pulling the shoulder blades down (not back) engages the lower trapezius without popping the ribs forward.
  • Correct movement avoids excessive rib elevation, which reduces lower trapezius activation.

Key Terms & Definitions

  • Trapezius — a large muscle in the upper back responsible for moving, rotating, and stabilizing the shoulder blade.
  • Scapula (shoulder blade) — the flat bone that connects the upper arm to the collarbone.
  • Elevation — upward movement of the shoulder blades.
  • Retraction — pulling the shoulder blades toward the spine.
  • Depression — pulling the shoulder blades downward.

Action Items / Next Steps

  • Practice setting your shoulder blades by pulling them together and then downward.
  • Focus on activating the middle and lower trapezius during exercises.