muscles of the shoulder girdle

Pectoralis major

Origin: Clavicle, sternum, and costal cartilages of upper ribs

Insertion: Intertubercular sulcus of humerus

Action: Flexes, adducts, medially rotates arm

Teres major

Origin: Lateral border of scapula

Insertion: Intertubercular sulcus of humerus

Action: Extends, adducts, medially rotates arm

Latissimus dorsi

Origin: Spinous processes of lower thoracic and lumbar vertebrae, iliac crest, and lower ribs

Insertion: Intertubercular sulcus of humerus

Action: Extends, aDDucts, medially rotates arm

Supraspinatus

Origin: Supraspinous fossa of scapula

Insertion: Greater tubercle of humerus

Action: Abducts arm

Deltoid

Origin: Acromion process, spine of scapula, clavicle

Insertion: Deltoid tuberosity of humerus

Action: abduct, flexes, extends arm at shoulder

Subscapularis

Origin: Anterior surface of scapula

Insertion: Lesser tubercle of humerus

Action: Medially rotates arm

Infraspinatus

Origin: Infraspinous fossa of scapula

Insertion: Greater tubercle of humerus

Action: Laterally rotates arm

Teres minor

Origin: Lateral border of scapula

Insertion: Greater tubercle of humerus

Action: Laterally rotates arm

Biceps brachii

Origin: Coracoid process (short head); tubercle above glenoid cavity of scapula (long head)

Insertion: Radial tuberosity

Action: Flexes forearm at elbow; supinates forearm and hand

Triceps brachii

Origin: Tubercle below glenoid cavity of scapula (long head); lateral surface of humerus (lateral head); posterior surface of humerus (medial head)
Insertion: Olecranon process of ulna
Action: Extends forearm at elbow

Trapezius

Origin: Occipital bone, ligamentum nuchae, and spinous processes of C7 and all thoracic vertebrae
Insertion: Clavicle, spine and acromion process of scapula
Action: rotates and retracts scapula, superior portion elevates scapula, inferior portion depresses scapula

Rhomboid major

Origin: spinous processes of upper thoracic vertebrae

insertion: medial border of scapula

Action: elevates and retracts scapula

levator scapulae

Origin: Transverse processes of cervical vertebrae

Insertion: Superior angle and medial border of scapula

Action: Elevates scapula

Serratus anterior

Origin: Anterior surfaces of ribs 1–10

Insertion: Medial border of scapula

Action: Protracts and rotates scapula

Pectoralis minor

Origin: Anterior surfaces of ribs 3–5

Insertion: Coracoid process of scapula

Action: Depresses and protracts scapula; elevates ribs during forceful inhalation