Pectoralis major
Latin: M. pectoralis major sinistra
Location: Chest
Paired structure: one on the left and one on the right side of the body.
View the pectoralis major in 3DOrigin
Clavicular head: medial half of the clavicle. Sternal head: sternum, costal cartilages 1–6, aponeurosis of the external oblique.
Insertion
Lateral lip of the intertubercular (bicipital) groove of the humerus, folding over itself so the clavicular head lies anterior.
Action
Adducts, flexes and medially rotates the arm — the hugging and throwing muscle. Its clavicular head flexes the raised arm; sternal head extends it from flexion.
Nerve supply
Lateral (C5–C7) and medial (C8–T1) pectoral nerves.
Blood supply
Pectoral branch of the thoracoacromial artery; internal thoracic perforators.
Clinical relevance
Pectoralis major ruptures occur during bench-press overload with a pop, bruising and an asymmetrical anterior axillary fold. The historical Halsted radical mastectomy removed the muscle; modern mastectomy preserves it.
Educational anatomy reference, not medical advice. About this content.