Pectoralis Major Muscle

Pectoralis major is a main anterior axial muscle. It has got two heads; the clavicular head and sternocostal head. The sternocostal head is the major head that forms most of the muscle. Pectoralis major forms the anterior axillary fold inferiorly. It also produces a deltopectoral groove along with the deltoid muscle, a pathway for the cephalic vein.

Anterior View

Pectoralis Major Muscle Rectus Abdominis Muscle External Oblique Muscle Serratus Anterior Muscle Deltoid Muscle

Pectoralis Major Muscle

SHAPE

It is a fan shaped large muscle.

ORIGIN AND INSERTION

Pectoralis major originates from its two heads. Clavicular head arises from medial half of anterior surface of clavicle and sternocostal head arises from anterior of sternum, aponeurosis of external oblique muscle and upper six costal cartilages.

The insertion point of this muscle is lateral lip of intertubercular sulcus of humerus.

NERVE SUPPLY

Pectoralis major is innervated by lateral and medial pectoral nerves.

BLOOD SUPPLY

The blood supply is provided by pectoral branch of thoracoacromial trunk.

FUNCTIONS

Pectoralis major is a very important muscle with significant actions. It causes adduction and medial rotation of humerus along with drawing scapula inferiorly. When clavicular head acts alone, it flexes the humerus.

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