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Shoulder Muscles
origin, insertion, action
| Term | Definition |
|---|---|
| Upper Trapezius | O: occipital protuberance & ligamentum nuchae I: lateral 1/3 of clavicle and acromion A: elevates & upwardly rotates scapula; unilaterally, laterally flexes head & rotates head to opposite side; bilaterally extends head |
| Middle Trapezius | O: spinous process of T1-T5 I: superior border of scapular spine A: adducts scapula |
| Lower Trapezius | O: spinous process of T6-T12 I: superior margin of medial 1/3 of scapular spine A: depresses, adducts, & upwardly rotates scapula |
| Anterior Deltoid | O: anterior lateral 1/3 of clavicle I: deltoid tuberosity A: ABD, horizontal ADD, & IR shoulder |
| Middle Deltoid | O: acromion process I: deltoid tuberosity A: shoulder ABD |
| Posterior Deltoid | O: inferior scapular spine I: deltoid tuberosity A: shoulder ABD, horizontal ABD & external rotation |
| Rhomboid Major | O: spinous process of T2-T5 I: vertebral border of scapula below spine of scapula A: elevates, downwardly rotates, & ADD scapula |
| Rhomboid Minor | O: spinous processes of C7-T1 I: vertebral border of scapula above spine of scapula A: elevates, downwardly rotates, & ADD scapula |
| Latissimus Dorsi | O: T7-L5: iliac crest; ribs 8-12; inferior angle of scapula I: bicipital groove of humerus A: extends, ADD, & IR shoulder |
| Teres Major | O: lower 1/3 of axillary border of scapula I: lesser tubercle; medial lip of bicipital groove of humerus A: shoulder ADD & internal rotation |
| Pectoralis Major | O: medial 1/2 of clavicle; sternum, costochondral cartilage of ribs 2-6 I: greater tubercle; lateral lip of bicipital groove of humerus A: flexes, ADD, & internally rotates shoulder |
| Pectoralis Minor | O: ribs 3-5 I: coracoid process A: tilts scapula anterior; downwardly rotates scapula |
| Supraspinatus | O: supraspinous fossa I: greater tubercle A: ABD shoulder |
| Infraspinatus | O: infraspinous fossa I: greater tubercle of humerus A: externally rotates shoulder |
| Subscapularis | O: subscapular fossa I: lesser tubercle of humerus A: internally rotates shoulder |
| Teres Minor | O: superior 2/3 of axillary border of scapula I: greater tubercle of humerus A: externally rotates shoulder |
| Serratus Anterior | O: superior lateral surfaces of ribs 1-9 I: anterior vertebral border of scapula A: upwardly rotates scapula; stabilizes vertebral border of scapular against ribcage |
| Biceps Brachii | O: Long Head: supraglenoid tubercle of scapula; Short Head: coracoid process I: radial tuberosity A: flexes & ABD shoulder; flexes elbow; supinates forearm |
| Triceps Brachii | O: Long Head: infraglenoid tubercle of scapula; Lateral Head: superior posterior 1/2 of humerus; Short Head: inferior 2/3 of posterior humerus I: olecranon process of ulna A: extends elbow; extends & ADD shoulder (long head only) |