Pronator Teres

Origin: Medial epicondyle of humerus and coronoid process of ulna
Insertion: Middle of lateral surface of radius
Action: Pronates and flexes forearm (at elbow)
Innervation: Median nerve (C6 and C7)
Arterial Supply: Ulnar artery, anterior recurrent ulnar artery

Rhomboid Major and Minor

Origin: Minor: nuchal ligament and spinous processes of C7 and T1 vertebrae; Major: spinous processes of T2 - T5 vertebrae
Insertion: Medial border of scapula from level of spine to inferior angle
Action: Retract scapula and rotate it to depress glenoid cavity; fix scapula to thoracic wall
Innervation: Dorsal scapular nerve ( C4 and C5)
Arterial Supply: Dorsal scapular artery

Trapezius

Origin: Medial third of superior nuchal line; external occipital protruberance, nuchal ligament, and spinous processes of C7 - T12 vertebrae
Insertion: Lateral third of clavicle, acromion, and spine of scapula
Action: Elevates, retracts and rotates scapula; superior fibers elevate, middle fibers retract, and inferior fibers depress scapula; superior and inferior fibers act together in superior rotation of scapula

Serratus Anterior

Origin: Superolateral surfaces of upper 8 or 9 ribs at the side of chest
Insertion: Vertebral border of scapula
Action: Draws scapula forward and upward; abducts scapula and rotates it; stabilizes vertebral border of scapula

Latissimus Dorsi

Origin: Superolateral surfaces of upper 8 or 9 ribs at the side of chest
Insertion: Vertebral border of scapula
Action: Draws scapula forward and upward; abducts scapula and rotates it; stabilizes vertebral border of scapula

Pectoralis Minor

Origin: 3rd to 5th ribs near their costal cartilages
Insertion: Medial border and superior surface of coracoid process of scapula
Action: Stabilizes scapula by drawing it inferiorly and anteriorly against thoracic wall

Pectoralis Major

Origin: Clavicular head: anterior surface of medial half of clavicle; Sternocostal head: anterior surface of sternum, superior six costal cartilages, and aponeurosis of external oblique muscle
Insertion: Lateral lip of intertubercular groove of humerus
Action: Adducts and medially rotates humerus; draws scapula anteriorly and inferiorly; Acting alone: clavicular head flexes humerus and sternocostal head extends it