Pectoralis Major: Origin, Insertion, Nerve Supply & Action

Pectoralis Major: The pectoralis major muscle is a thick, fan-shaped, situated anteriorly at the chest of the human body. It makes up the bulk of the chest muscles in the male and lies under the breast in case of the female. Underneath the pectoralis major is the pectoralis minor muscle, a thin, triangular muscle. In sports as well as bodybuilding, the pectoral muscles may be referred to as “pecs”, “pectoral muscle” or “chest muscle”.

Attachments of the Pectoralis Major Muscle

Origin:
Clavicular head: medial half of the clavicle.Sternal head: sternum, upper costal cartilages (1-6), and aponeurosis of the external oblique
Sternal head: sternum, upper costal cartilages (1-6), and aponeurosis of the external oblique

Insertion:
Lateral lip of the bicipital (intertubercular) groove of the humerus.
Crest of the greater tubercle of the humerus. Coracoid process of the scapula

Function of the Pectoralis Major Muscle

Draws scapula anteriorly and inferiorly;
Adducts and medially rotates humerus;
Acting alone: clavicular head flexes humerus and sternocostal head extends it