Presentation on theme: "Muscles Acting on Shoulder Comparative Analysis: Strongest to Weakest"— Presentation transcript:
1Muscles Acting on Shoulder Comparative Analysis: Strongest to Weakest
2A. Adduction 1. Pectoralis Major 2. (long head) Triceps 3. Teres Major 1. Pectoralis Major2. (long head) Triceps3. Teres Major4. Latissimus Dorsi5. (short head) Biceps6. Clavicular and spinal parts of deltoidAdduction notes: Trail Guide also listsTeres minor and coracobrachialisstrongest to weakest: red, blue, yellow, orange, green, brown
3B. Abduction 1. Deltoid 2. Supraspinatus (long head) biceps * strongest to weakest: red, blue, yellow, orange, green, brown1. Deltoid2. Supraspinatus(long head)biceps ** Trail Guide does NOT list (long head) biceps
4C. Elevation: a continuation of abduction above 90 degrees --- requires upward rotation of scapula strongest to weakest: red, blue, yellow1. Serratus Anterior2. Trapezius (in the transition from abduction to elevation, the trapezius supports serratus anterior)Before elevation… need to abduct:1. Deltoid2. Supraspinatus3. (long head) biceps
5What drives upward rotation of the scapula? During the early phase of upward rotation, the scapula and the clavicle move togetherSerratus anterior (SA) and upper trapezius (UT) produce upward rotation momentsOnce 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.
6Anteversion = Flexion of the glenohumeral joint 1. Deltoid (anterior fibers)2. Biceps Brachii3. Pectoralis Major4. Coracobrachialis5. Serratus Anterior ** Trail Guide does NOT listSerratus Anterior