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Pectoralis major
Main human chest muscle / From Wikipedia, the free encyclopedia
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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.
Pectoralis major | |
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![]() 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 |
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.