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Muscles Acting on Shoulder Comparative Analysis: Strongest to Weakest. A. Ad duction. strongest to weakest: red, blue, yellow, orange, green, brown. 1. Pectoralis Major 2. (long head) Triceps 3. Teres Major 4. Latissimus Dorsi 5. (short head) Biceps
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Muscles Acting on ShoulderComparative Analysis:StrongesttoWeakest
A. Adduction strongest to weakest: red, blue, yellow, orange, green, brown 1. Pectoralis Major 2. (long head) Triceps 3. Teres Major 4. Latissimus Dorsi 5. (short head) Biceps 6. Clavicular and spinal parts of deltoid Adduction notes: Trail Guide also lists Teres minor and coracobrachialis
B. Abduction strongest to weakest: red, blue, yellow, orange, green, brown • 1.Deltoid • 2. Supraspinatus • (long head) • biceps * * Trail Guide does NOT list (long head) biceps
C. Elevation: a continuation of abduction above 90 degrees --- requires upward rotation of scapula strongest to weakest: red, blue, yellow 1. Serratus Anterior 2. Trapezius (in the transition from abduction to elevation, the trapezius supports serratus anterior) Before elevation… need to abduct: 1. Deltoid 2. Supraspinatus 3. (long head) biceps
What drives upward rotation of the scapula? During the early phase of upward rotation, the scapula and the clavicle move together Serratus anterior (SA) and upper trapezius (UT) produce upward rotation moments Once tension in the costoclavicular ligament prevents further elevation of the clavicle at the sternoclavicular joint, the axis for scapular rotation moves to the acromioclavicular (AC) joint. Serratus anterior (SA) and the lower trapezius (LT) produce upward rotation moments.
Anteversion = Flexion of the glenohumeral joint 1. Deltoid (anterior fibers) 2. Biceps Brachii 3. Pectoralis Major 4. Coracobrachialis 5. Serratus Anterior * * Trail Guide does NOT list Serratus Anterior
Retroversion = extension 1. Teres Major 2. Latissimus Dorsi 3. (long head) Triceps 4. Deltoid (posterior) Trail Guide also lists: Infraspinatus, Teres Minor, Pectoralis Major (lower)
Lateral Rotation 1. Infraspinatus 2. Teres Minor 3. Deltoid
Medial Rotation 1. Subscapularis 2. Pectoralis Major 3. (long head) Biceps * 4. Deltoid (anterior) 5. Teres Major 6. Latissimus Dorsi * Trail Guide does NOT list: (long head) Biceps