Pectoralis major

Pectoralis major
Superficial muscles of the chest and front of the arm
The trunk viewed from the front, showing the pectoralis major to the right (To the left it is removed showing underlying structures, among other the pectoralis minor.)
Details
Pronunciation	/ˌpɛktəˈreɪlɪs ˈmeɪdʒər/
Origin	Clavicular head: anterior surface of the medial half of the clavicle. Sternocostal head: anterior surface of the sternum, the superior six costal cartilages, and the aponeurosis of the external oblique muscle
Insertion	Lateral lip of the bicipital groove of the humerus (anteromedial proximal humerus)
Artery	Pectoral branch of the thoracoacromial trunk
Nerve	Lateral pectoral nerve and medial pectoral nerve Clavicular head: C5 and C6 Sternocostal head: C7, C8 and T1
Actions	Clavicular head: flexes the humerus Sternocostal head: horizontal and vertical adduction, extension, and internal rotation of the humerus Depression and abduction of the scapula.[1]
Antagonist	Deltoid muscle, trapezius
Identifiers
Latin	musculus pectoralis major
TA98	A04.4.01.002
TA2	2301
FMA	9627
Anatomical terms of muscle [edit on Wikidata]

The pectoralis major (from Latin pectus 'breast') is a thick, fan-shaped or triangular convergent muscle of the human chest. It makes up the bulk of the chest muscles and lies under the breast. Beneath the pectoralis major is the pectoralis minor muscle.

The pectoralis major arises from parts of the clavicle and sternum, costal cartilages of the true ribs, and the aponeurosis of the abdominal external oblique muscle; it inserts onto the lateral lip of the bicipital groove. It receives double motor innervation from the medial pectoral nerve and the lateral pectoral nerve. The pectoralis major's primary functions are flexion, adduction, and internal rotation of the humerus. The pectoral major may colloquially be referred to as "pecs", "pectoral muscle", or "chest muscle", because it is the largest and most superficial muscle in the chest area.