These muscles stabilise the association between the appendicular and axial skeletons, and stabilise and allow movement of the shoulders and upper arms.
| Muscle | Origin | Insertion | Action |
| Deltoid | Lateral one-third of the clavicle Acromion Lower lip of the crest of the spine of the scapula | Deltoid tuberosity of the humerus | Abducts arm Anterior fibres flex & medially rotate the arm Posterior fibres extend Laterally rotate the arm |
| Muscle | Origin | Insertion | Action |
| Supraspinatus | Supraspinatus fossa | Greater tubercle of the humerus (highest facet) | Abducts the arm (initiates abduction) |
| Muscle | Origin | Insertion | Action |
| Subscapularis | Medial two-thirds of the costal surface of the scapula (sub-scapular fossa) | Lesser tubercle of the humerus | Medially rotates the arm Assists extension of the arm |
| Muscle | Origin | Insertion | Action |
| Infraspinatus | Infraspinatus fossa | Greater tubercle of the humerus (middle facet) | Laterally rotates the arm |
| Muscle | Origin | Insertion | Action |
| Teres minor | Upper 2/3 of the lateral border of the scapula | Greater tubercle of the humerus (lowest facet) | Laterally rotates the arm |
| Muscle | Origin | Insertion | Action |
| Pectoralis major | Medial 1/2 of the clavicle, manubrium Body of sternum Costal cartilages of ribs 2-6, sometimes from the rectus sheath of the upper abdominal wall | Crest of the greater tubercle of the humerus | Flexes and adducts the arm Medially rotates the arm |
| Muscle | Origin | Insertion | Action |
| Rhomboid Major | Spines of vertebrae T2-T5 | Medial border of the scapula inferior to the spine of the scapula | Retracts, elevates and rotates the scapula inferiorly |
| Muscle | Origin | Insertion | Action |
| Rhomboid Minor | Inferior end of the ligamentum nuchae Spines of vertebrae C7 and T1 | Medial border of the scapula at the root of the spine of the scapula | Retracts, elevates and rotates the scapula inferiorly |
| Muscle | Origin | Insertion | Action |
| Biceps Brachii | Short head: tip of the coracoid process of the scapula Long head: supra-glenoid tubercle of the scapula | Tuberosity of the radius | Flexes the forearm Flexes arm (long head) |
| Muscle | Origin | Insertion | Action |
| Brachialis | Anterior surface of the lower one-half of the humerus and the associated inter-muscular septa | Coronoid process of the ulna | Flexes the forearm |
| Muscle | Origin | Insertion | Action |
| Brachioradialis | Upper two-thirds of the lateral supracondylar ridge of the humerus | Lateral side of the base of the styloid process of the radius | Flexes the elbow, Assists in pronation & supination |
| Muscle | Origin | Insertion | Action |
| Coracobrachialis | Coracoid process of the scapula | Medial side of the humerus at mid-shaft | Flexes and adducts the arm |
| Muscle | Origin | Insertion | Action |
| Triceps Brachii | Long head: infra-glenoid tubercle of the scapula Lateral head: posterolateral humerus & lateral inter-muscular septum Medial head: posteromedial surface of the inferior 1/2 of the humerus | Olecranon process of the ulna | Extends the forearm Long head extends and adducts arm |
| Muscle | Origin | Insertion | Action |
| Serratus Anterior | Ribs 1-8 or 9 | Medial border of the scapula on its costal (deep) surface | Draws the scapula forward Inferior fibers rotate the scapula superiorly |
