overview

Origin

Anterior surface and medial half of clavicle (clavicular head)

Anterior surface of sternum (sternocostal head)

Superior six costal cartilages (sternocostal head)

Aponeurosis of external oblique muscle (sternocostal head)

Insertion

The lateral lip of the bicipital groove

Action

Adduction of humerus at shoulder joint

Medial rotation of humerus at shoulder joint

Flexion of humerus at shoulder joint (clavicular head)

Extension of humerus at shoulder joint (sternocostal head)

Nerve

Medial pectoral nerve (C8 & T1)

Lateral pectoral nerve (C5, C6, & C7)

Artery

Pectoral branch of the thoracoacromial artery