What movements are performed by the upper fibers of the trapezius muscle?

Upper Trapezius Muscle Movements

The upper fibers of the trapezius muscle are primarily responsible for elevation of the scapula through clavicular elevation and retraction, rather than direct scapular elevation as commonly misunderstood. 1

Primary Actions

Scapular Elevation via Clavicular Rotation

• The upper trapezius produces clavicular elevation and retraction, which indirectly raises the scapula by rotating the clavicle about the sternoclavicular joint 1
• The occipital and nuchal fibers pass downwards but mainly transversely to insert into the clavicle, not vertically as traditionally depicted 1
• This transverse orientation means the upper trapezius cannot directly elevate the scapula as commonly shown in anatomy texts 1

Scapular Upward Rotation

• The upper trapezius contributes to scapular upward rotation during arm elevation, working synergistically with the serratus anterior 2, 3
• This upward rotation is most pronounced during the mid-range (90-120 degrees) of arm elevation 2
• The upper trapezius is considered one of only two muscle groups (along with serratus anterior) that produce upward rotation of the scapula 3

Backward Retraction of Scapula

• The essentially transverse fiber orientation allows the upper trapezius to draw the scapula and clavicle backwards 1
• This action helps maintain proper scapular positioning during shoulder movements 4

Biomechanical Function

Cervical Spine Protection

• By balancing moments, the trapezius relieves the cervical spine of compression loads 1
• This protective mechanism is critical during activities requiring sustained shoulder positioning 1

Synergistic Muscle Activity

• The trapezius operates as a dominant stabilizer of the scapula, normally working synergistically with the serratus anterior 4
• During active arm elevation, increased upper trapezius activity produces more clavicular elevation and external rotation of the scapula compared to passive movement 2

Clinical Relevance

Pathological Patterns

• Increased activation of the upper trapezius has been identified in subjects with shoulder impingement compared to healthy controls 5
• Altered activation or poor control of the upper trapezius has been linked with abnormal scapular movements often associated with pain 4

Exercise Targeting

• The unilateral shoulder shrug exercise produces the greatest EMG activity in the upper trapezius 3
• Assessment of upper trapezius function and scapular upward rotation should be part of any shoulder examination 2