The pectoralis major is a muscle of the anterior chest wall. It is a large fan-shaped muscle, which is composed of a sternal head and a clavicular head.
- Clavicular head originates from the anterior surface of the medial clavicle.
- Sternocostal head originates from the anterior surface of the sternum, the superior six costal cartilages and the aponeurosis of the external oblique muscle.
- The distal attachment of both heads is onto the intertubercular sulcus of the humerus.
- Function: Adduction and medial rotation of the upper limb.
- Innervation: Lateral and medial pectoral nerves.
- Blood supply: Pectoral branch of thoracoacromial artery, superior thoracic artery, lateral thoracic artery.