Muscle Origin Insertion Action
Deltiod(anterior) Lateral 1/3 of clavicle Deltoid tuberosity of humerus Abduction, horizontal flexion, medial rotation (of humerus at shoulder)
Deltoid(middle) Superior surface of acromion process Tuberosity of humerus Abduction of shoulder
Deltoid(posterior) Inferior part of spine of scapula Tuberosity of humerus Abduction, horizontal extension and lateral rotation of shoulder
Pectoralis major(sternal) Sternum to 7th rib, artilae of tru ribs, external oblique muscles Humerus Flexion, adduction, medial rotation, horizontal flexion of shoulder; Depresses, protracts and rotates scapula downwards
Pectoralis major(clavicular) Anterior surface of medial 1/2 of clavicle Humerus Flexion, adduction, horizontal flexion, medial rotation of shoulder
Coracobrachialis Tip of coracoid process of scapula Middle medial border of humerus Horizontal flexion, adduction of shoulder
Latissimus dorsi Lower 6 thoracic vertebra, all lumbar vertebrae, posterior crest of ilium, posterior surface of sacrum, lower 3-4 ribs, iniferior angles of scapula Humerus Extends, retracts, medially rotates shoulder; depresses, retracts and rotates scapula downwards. Assists in forced expiration.
Teres Major Dorsal surface of inferior angle of scapula on lower 1/2 of scapular border Medial part of humerus Adducts, medially rotates humerus at shoulder. Extends shoulds.
Supraspinatus (Rotator cuff) Medial 2/3 of supraspinous fossa Superior surface of humerus Abduction of humerus at shoulder
Infraspinatus (Rotator cuff) Infraspinous fossa of scapula Posterior part of humerus Lateral rotation of humerus at shoulder
Teres minor (Rotator cuff) Superior 2/3 of dorsal surface of border of scapula Inferior part of humerus Lateral rotation of humerus at shoulder
Subscapularis(Rotator Cuff) Anterior surface of subscapular fossa Lesser rubercles of humerus Medial rotation of humerus at shoulder