Muscle | Origin | Insertion | Movement | Joint | Misc. Info |
Deltoid (anterior) | Lateral third of clavicle | Deltoid tuberosity of humerus | Flexion, medial rotation | Anterior | One compartment of the deltoid |
Biceps brachii | Long head-supraglenoid tubercle of scapula; short head-coracoid process of scapula | Radial tuberosity | Flexion; short head-synergist for abduction | Anterior, inferior to shoulder | Long head runs through intubercular groove; fibrous lacertus: sheath of connective tissue that allows biceps brachii to have multiple actions |
Coracobrachialis | Coracoid process of scapula | Anteromedial humerus (medial to deltoid tuberosity) | Flexion, adduction | Anterior, deep to biceps brachii | Shares a tendon with biceps brachii |
Trapezius (upper) | External occipital protuberance (superior nuchal lines) | Lateral third of clavicle | Elevation, upward rotation | Posterior, superficial (spine/scapula) | One of four divisions of trapezius |
Trapezius (upper middle) | Ligamentum nuchae | Acromion process | Elevation, retraction | Posterior, superficial (spine/scapula) | One of four divisions of trapezius |
Trapezius (lower middle) | Spinous processes of thoracic vertebrae (6-12) | Lateral/middle scapular spine | Retraction | Posterior, superficial (spine/scapula) | One of four divisions of trapezius |
Trapezius (lower) | Spinous processes of thoracic vertebrae (6-12) | Medial edge of scapular spine | Depression, upward rotation | Posterior, superficial (spine/scapula) | One of four divisions of trapezius |
Latissimus dorsi | Spinous processes of lower thoracic/lumbar vertebrae via thoracolumbar fascia, iliac crest | Medial lip of intertubercular groove (twists) | Extension, adduction, medial rotation | Posterior, superficial (spine/scapula) | Forms posterior portion of axilla; "swimmer's muscle"; projects laterally, superiorly, under arm |
Levator scapulae | Transverse processes of cervical vertebrae (C1-C4) | Superior angle of scapula (twist) | Elevation, downward rotation; lateral flexion, ipsilateral rotation (fixed scapula) | Posterior, deep (spine/scapula) | |
Rhomboids (minor and major) | C7, thoracic vertebrae (minor superior to major) | Medial border of scapula (where levator scapulae ends) | Retraction, downward rotation, elevation | Posterior, deep (spine/scapula) | Role in scapulohumeral rhythm; stabilizes scapula when using pectoralis major |
Serratus anterior | Anterolateral ribs | Medial border and inferior angle of scapula (anterior surface) | Protraction, upward rotation (interior fibers); holds medial border firmly against thorax (prevents "winging") | Deep (spine/scapula) | "Boxer's muscle" |
Deltoid (posterior) | Inferior border of scapular spine | Deltoid tuberosity of humerus | Extension/hyperextension, lateral rotation | Posterior, superficial (scapula/humerus) | |
Deltoid (middle) | Acromion process | Deltoid tuberosity of humerus | Abduction (prime mover, anterior and posterior deltoid are synergists) | Superficial (scapula/humerus) | |
Subscapularis | Subscapular fossa | Lesser tubercle of humerus | Medial rotation | Rotator cuff | |
Supraspinatus | Supraspinous fossa | Greater tubercle of humerus | Abduction | Rotator cuff | Tendon is usually cause of "rotator cuff injuries" |
Infraspinatus | Infraspinous fossa | Greater tubercle of humerus | Lateral rotation | Rotator cuff | Acts with teres minor |
Teres minor | Lateral border of scapula | Greater tubercle of humerus (inferior to infraspinatus) | Lateral rotation | Rotator cuff | Acts with infraspinatus |
Teres major | Inferior angle of scapula | Medial lip of intertubercular groove (anterior surface) (same-ish as latissimus dorsi) | Extension, adduction, medial rotation | Glenohumeral (posterior, deep) | "Lat's little helper"; inserts inferior to teres minor |
Triceps brachii (long head) | Infraglenoid tubercle of scapula | Olecranon process | Shoulder extension | | Only muscle on posterior arm; only head to produce shoulder movements |
Pectoralis major | Sternal head-sternum (~rib 1-7); clavicular head-medial third of clavicle | Lateral lip of intubercular groove (sternal superior to clavicular) | (Both) adduction, medial rotation; (clavicular) flexion; (sternal) extension | Anterior, superficial | Forms anterior border of axilla; major muscle of upper trunk; |
Pectoralis minor | Anterior surface of ribs (3-5) | Coracoid process | Protraction, depression, downward rotation; pull ribcage superiorly (if scapula fixed) | Anterior, deep to pectoralis major | Smaller than pectoralis major |