Presentation on theme: "Muscles Acting on Shoulder Comparative Analysis: Strongest to Weakest."— Presentation transcript:
Muscles Acting on Shoulder Comparative Analysis: Strongest to Weakest
1. Pectoralis Major 2. (long head) Triceps Teres Major 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 strongest to weakest: red, blue, yellow, orange, green, brown A. Adduction
strongest to weakest: red, blue, yellow, orange, green, brown B. Abduction 1. Deltoid 2. Supraspinatus 3.(long head) biceps biceps * * Trail Guide does NOT list (long head) biceps
strongest to weakest: red, blue, yellow C. Elevation: a continuation of abduction above 90 degrees --- requires upward rotation of scapula 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 (long head) biceps 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 Pectoralis Major 3. Pectoralis Major 4. Coracobrachialis 5. Serratus Anterior * * Trail Guide does NOT list Serratus Anterior
1. Teres Major 2. Latissimus Dorsi (long head) Triceps 3. (long head) Triceps 4. Deltoid (posterior) Retroversion = extension Trail Guide also lists: Infraspinatus, Teres Minor, Pectoralis Major (lower)